Editorial

8 pages, 218 KiB

Open AccessEditorial

Nanotechnologies and Nanomaterials: Selected Papers from CCMR

by Ming-Yu Li and Jihoon Lee

Nanomaterials 2024, 14(1), 36; https://doi.org/10.3390/nano14010036 - 22 Dec 2023

Viewed by 649

Nanomaterial technology for the synthesis, processing, and fabrication of low-dimensional materials is where disciplines merge into a remarkable range of applications, from optoelectronics to health care (contribution 1–7), which affect the lives of millions [...] Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

Research

Jump to: Editorial, Review

15 pages, 5395 KiB

Open AccessArticle

A Study on the Dynamic Tunning Range of CVD Graphene at Microwave Frequency: Determination, Prediction and Application

by Hao Chen, Zhen-Guo Liu, Ming-Yang Geng, Xiang-Yu Meng, Wan-Lin Fu, Lu Ju, Bu-Yun Yu, Wu Yang, Yun-Qian Dai and Wei-Bing Lu

Nanomaterials 2022, 12(24), 4424; https://doi.org/10.3390/nano12244424 - 11 Dec 2022

Viewed by 983

Abstract

In recent years, graphene has shown great application prospects in tunable microwave devices due to its tunable conductivity. However, the electromagnetic (EM) properties of graphene, especially the dynamic tunning characteristics, are largely dependent on experimental results, and thus are unable to be effectively [...] Read more.

In recent years, graphene has shown great application prospects in tunable microwave devices due to its tunable conductivity. However, the electromagnetic (EM) properties of graphene, especially the dynamic tunning characteristics, are largely dependent on experimental results, and thus are unable to be effectively predicted according to growth parameters, which causes great difficulties in the design of graphene-based tunable microwave devices. In this work, we systematically explored the impact of chemical vapor deposition (CVD) parameters on the dynamic tunning range of graphene. Firstly, through improving the existing waveguide method, the dynamic tunning range of graphene can be measured more accurately. Secondly, a direct mathematical model between growth parameters and the tunning range of graphene is established. Through this, one can easily obtain needed growth parameters for the desired tunning range of graphene. As a verification, a frequency tunable absorber prototype is designed and tested. The good agreement between simulation and experimental results shows the reliability of our mathematic model in the rapid design of graphene-based tunable microwave devices. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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16 pages, 3374 KiB

Open AccessArticle

High Performance 0D ZnO Quantum Dot/2D (PEA)₂PbI₄ Nanosheet Hybrid Photodetectors Fabricated via a Facile Antisolvent Method

by Shijie Liu, Hao Li, Haifei Lu, Yanran Wang, Xiaoyan Wen, Shuo Deng, Ming-Yu Li, Sisi Liu, Cong Wang and Xiao Li

Nanomaterials 2022, 12(23), 4217; https://doi.org/10.3390/nano12234217 - 27 Nov 2022

Cited by 1 | Viewed by 1458

Abstract

Two-dimensional (2D) organic−inorganic perovskites have great potential for the fabrication of next-generation photodetectors owing to their outstanding optoelectronic features, but their utilization has encountered a bottleneck in anisotropic carrier transportation induced by the unfavorable continuity of the thin films. We propose a facile [...] Read more.

Two-dimensional (2D) organic−inorganic perovskites have great potential for the fabrication of next-generation photodetectors owing to their outstanding optoelectronic features, but their utilization has encountered a bottleneck in anisotropic carrier transportation induced by the unfavorable continuity of the thin films. We propose a facile approach for the fabrication of 0D ZnO quantum dot (QD)/2D (PEA)₂PbI₄ nanosheet hybrid photodetectors under the atmospheric conditions associated with the ZnO QD chloroform antisolvent. Profiting from the antisolvent, the uniform morphology of the perovskite thin films is obtained owing to the significantly accelerated nucleation site formation and grain growth rates, and ZnO QDs homogeneously decorate the surface of (PEA)₂PbI₄ nanosheets, which spontaneously passivate the defects on perovskites and enhance the carrier separation by the well-matched band structure. By varying the ZnO QD concentration, the Ion/Ioff ratio of the photodetectors radically elevates from 78.3 to 1040, and a 12-fold increase in the normalized detectivity is simultaneously observed. In addition, the agglomeration of perovskite grains is governed by the annealing temperature, and the photodetector fabricated at a relatively low temperature of 120 °C exhibits excellent stability after a 50-cycle test in the air condition without any encapsulation. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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9 pages, 820 KiB

Open AccessArticle

Low-Power Complementary Inverter Based on Graphene/Carbon-Nanotube and Graphene/MoS₂ Barristors

by Dong-Ho Shin, Young Gyu You, Sung Il Jo, Goo-Hwan Jeong, Eleanor E. B. Campbell, Hyun-Jong Chung and Sung Ho Jhang

Nanomaterials 2022, 12(21), 3820; https://doi.org/10.3390/nano12213820 - 28 Oct 2022

Cited by 2 | Viewed by 1466

Abstract

The recent report of a p-type graphene(Gr)/carbon-nanotube(CNT) barristor facilitates the application of graphene barristors in the fabrication of complementary logic devices. Here, a complementary inverter is presented that combines a p-type Gr/CNT barristor with a n-type Gr/MoS

_{2}

barristor, and its characteristics are [...] Read more.

The recent report of a p-type graphene(Gr)/carbon-nanotube(CNT) barristor facilitates the application of graphene barristors in the fabrication of complementary logic devices. Here, a complementary inverter is presented that combines a p-type Gr/CNT barristor with a n-type Gr/MoS

_{2}

barristor, and its characteristics are reported. A sub-nW (~0.2 nW) low-power inverter is demonstrated with a moderate gain of 2.5 at an equivalent oxide thickness (EOT) of ~15 nm. Compared to inverters based on field-effect transistors, the sub-nW power consumption was achieved at a much larger EOT, which was attributed to the excellent switching characteristics of Gr barristors. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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10 pages, 1405 KiB

Open AccessArticle

Indirect Band Gap in Scrolled MoS₂ Monolayers

by Jeonghyeon Na, Changyeon Park, Chang Hoi Lee, Won Ryeol Choi, Sooho Choi, Jae-Ung Lee, Woochul Yang, Hyeonsik Cheong, Eleanor E. B. Campbell and Sung Ho Jhang

Nanomaterials 2022, 12(19), 3353; https://doi.org/10.3390/nano12193353 - 26 Sep 2022

Cited by 5 | Viewed by 2266

Abstract

MoS₂ nanoscrolls that have inner core radii of ∼250 nm are generated from MoS₂ monolayers, and the optical and transport band gaps of the nanoscrolls are investigated. Photoluminescence spectroscopy reveals that a MoS₂ monolayer, originally a direct gap semiconductor (∼1.85 [...] Read more.

MoS₂ nanoscrolls that have inner core radii of ∼250 nm are generated from MoS₂ monolayers, and the optical and transport band gaps of the nanoscrolls are investigated. Photoluminescence spectroscopy reveals that a MoS₂ monolayer, originally a direct gap semiconductor (∼1.85 eV (optical)), changes into an indirect gap semiconductor (∼1.6 eV) upon scrolling. The size of the indirect gap for the MoS₂ nanoscroll is larger than that of a MoS₂ bilayer (∼1.54 eV), implying a weaker interlayer interaction between concentric layers of the MoS₂ nanoscroll compared to Bernal-stacked MoS₂ few-layers. Transport measurements on MoS₂ nanoscrolls incorporated into ambipolar ionic-liquid-gated transistors yielded a band gap of ∼1.9 eV. The difference between the transport and optical gaps indicates an exciton binding energy of 0.3 eV for the MoS₂ nanoscrolls. The rolling up of 2D atomic layers into nanoscrolls introduces a new type of quasi-1D nanostructure and provides another way to modify the band gap of 2D materials. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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20 pages, 3455 KiB

Open AccessArticle

Vanadium-Doped FeBP Microsphere Croissant for Significantly Enhanced Bi-Functional HER and OER Electrocatalyst

by Shalmali Burse, Rakesh Kulkarni, Rutuja Mandavkar, Md Ahasan Habib, Shusen Lin, Young-Uk Chung, Jae-Hun Jeong and Jihoon Lee

Nanomaterials 2022, 12(19), 3283; https://doi.org/10.3390/nano12193283 - 21 Sep 2022

Cited by 3 | Viewed by 1959

Abstract

Ultra-fine hydrogen produced by electrochemical water splitting without carbon emission is a high-density energy carrier, which could gradually substitute the usage of traditional fossil fuels. The development of high-performance electrocatalysts at affordable costs is one of the major research priorities in order to [...] Read more.

Ultra-fine hydrogen produced by electrochemical water splitting without carbon emission is a high-density energy carrier, which could gradually substitute the usage of traditional fossil fuels. The development of high-performance electrocatalysts at affordable costs is one of the major research priorities in order to achieve the large-scale implementation of a green hydrogen supply chain. In this work, the development of a vanadium-doped FeBP (V-FeBP) microsphere croissant (MSC) electrocatalyst is demonstrated to exhibit efficient bi-functional water splitting for the first time. The FeBP MSC electrode is synthesized by a hydrothermal approach along with the systematic control of growth parameters such as precursor concentration, reaction duration, reaction temperature and post-annealing, etc. Then, the heteroatom doping of vanadium is performed on the best FeBP MSC by a simple soaking approach. The best optimized V-FeBP MSC demonstrates the low HER and OER overpotentials of 52 and 180 mV at 50 mA/cm² in 1 M KOH in a three-electrode system. In addition, the two-electrode system, i.e., V-FeBP || V-FeBP, demonstrates a comparable water-splitting performance to the benchmark electrodes of Pt/C || RuO₂ in 1 M KOH. Similarly, exceptional performance is also observed in natural sea water. The 3D MSC flower-like structure provides a very high surface area that favors rapid mass/electron-transport pathways, which improves the electrocatalytic activity. Further, the V-FeBP electrode is examined in different pH solutions and in terms of its stability under industrial operational conditions at 60 °C in 6 M KOH, and it shows excellent stability. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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24 pages, 13540 KiB

Open AccessFeature PaperArticle

Independent Dual-Channel Approach to Mesoscopic Graphene Transistors

by Fernando Sánchez, Vicenta Sánchez and Chumin Wang

Nanomaterials 2022, 12(18), 3223; https://doi.org/10.3390/nano12183223 - 16 Sep 2022

Viewed by 1064

Abstract

Graphene field-effect transistors (GFETs) exhibit unique switch and sensing features. In this article, GFETs are investigated within the tight-binding formalism, including quantum capacitance correction, where the graphene ribbons with reconstructed armchair edges are mapped into a set of independent dual channels through a [...] Read more.

Graphene field-effect transistors (GFETs) exhibit unique switch and sensing features. In this article, GFETs are investigated within the tight-binding formalism, including quantum capacitance correction, where the graphene ribbons with reconstructed armchair edges are mapped into a set of independent dual channels through a unitary transformation. A new transfer matrix method is further developed to analyze the electron transport in each dual channel under a back gate voltage, while the electronic density of states of graphene ribbons with transversal dislocations are calculated using the retarded Green’s function and a novel real-space renormalization method. The Landauer electrical conductance obtained from these transfer matrices was confirmed by the Kubo–Greenwood formula, and the numerical results for the limiting cases were verified on the basis of analytical results. Finally, the size- and gate-voltage-dependent source-drain currents in GFETs are calculated, whose results are compared with the experimental data. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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10 pages, 1718 KiB

Open AccessArticle

Simulation of Figures of Merit for Barristor Based on Graphene/Insulator Junction

by Jun-Ho Lee, Inchul Choi, Nae Bong Jeong, Minjeong Kim, Jaeho Yu, Sung Ho Jhang and Hyun-Jong Chung

Nanomaterials 2022, 12(17), 3029; https://doi.org/10.3390/nano12173029 - 31 Aug 2022

Cited by 1 | Viewed by 1411

Abstract

We investigated the tunneling of graphene/insulator/metal heterojunctions by revising the Tsu–Esaki model of Fowler–Nordheim tunneling and direct tunneling current. Notably, the revised equations for both tunneling currents are proportional to V³, which originates from the linear dispersion of graphene. We developed [...] Read more.

We investigated the tunneling of graphene/insulator/metal heterojunctions by revising the Tsu–Esaki model of Fowler–Nordheim tunneling and direct tunneling current. Notably, the revised equations for both tunneling currents are proportional to V³, which originates from the linear dispersion of graphene. We developed a simulation tool by adopting revised tunneling equations using MATLAB. Thereafter, we optimized the device performance of the field-emission barristor by engineering the barrier height and thickness to improve the delay time, cut-off frequency, and power-delay product. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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16 pages, 4755 KiB

Open AccessArticle

Deposition Mechanism and Characterization of Plasma-Enhanced Atomic Layer-Deposited SnO_x Films at Different Substrate Temperatures

by Pao-Hsun Huang, Zhi-Xuan Zhang, Chia-Hsun Hsu, Wan-Yu Wu, Sin-Liang Ou, Chien-Jung Huang, Dong-Sing Wuu, Shui-Yang Lien and Wen-Zhang Zhu

Nanomaterials 2022, 12(16), 2859; https://doi.org/10.3390/nano12162859 - 19 Aug 2022

Cited by 4 | Viewed by 1887

Abstract

The promising functional tin oxide (SnO_x) has attracted tremendous attention due to its transparent and conductive properties. The stoichiometric composition of SnO_x can be described as common n-type SnO₂ and p-type Sn₃O₄. In this study, [...] Read more.

The promising functional tin oxide (SnO_x) has attracted tremendous attention due to its transparent and conductive properties. The stoichiometric composition of SnO_x can be described as common n-type SnO₂ and p-type Sn₃O₄. In this study, the functional SnO_x films were prepared successfully by plasma-enhanced atomic layer deposition (PEALD) at different substrate temperatures from 100 to 400 °C. The experimental results involving optical, structural, chemical, and electrical properties and morphologies are discussed. The SnO₂ and oxygen-deficient Sn₃O₄ phases coexisting in PEALD SnO_x films were found. The PEALD SnO_x films are composed of intrinsic oxygen vacancies with O-Sn⁴⁺ bonds and then transformed into a crystalline SnO₂ phase with increased substrate temperature, revealing a direct 3.5–4.0 eV band gap and 1.9–2.1 refractive index. Lower (<150 °C) and higher (>300 °C) substrate temperatures can cause precursor condensation and desorption, respectively, resulting in reduced film qualities. The proper composition ratio of O to Sn in PEALD SnO_x films near an estimated 1.74 suggests the highest mobility of 12.89 cm² V⁻¹ s⁻¹ at 300 °C. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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17 pages, 3673 KiB

Open AccessArticle

Photocatalytic Activity of TiO₂/g-C₃N₄ Nanocomposites for Removal of Monochlorophenols from Water

by Thawanrat Kobkeatthawin, Suwilai Chaveanghong, Jirawat Trakulmututa, Taweechai Amornsakchai, Puangrat Kajitvichyanukul and Siwaporn Meejoo Smith

Nanomaterials 2022, 12(16), 2852; https://doi.org/10.3390/nano12162852 - 18 Aug 2022

Cited by 15 | Viewed by 2008

Abstract

This research employed g-C₃N₄ nanosheets in the hydrothermal synthesis of TiO₂/g-C₃N₄ hybrid photocatalysts. The TiO₂/g-C₃N₄ heterojunctions, well-dispersed TiO₂ nanoparticles on the g-C₃N₄ nanosheets, are effective photocatalysts [...] Read more.

This research employed g-C₃N₄ nanosheets in the hydrothermal synthesis of TiO₂/g-C₃N₄ hybrid photocatalysts. The TiO₂/g-C₃N₄ heterojunctions, well-dispersed TiO₂ nanoparticles on the g-C₃N₄ nanosheets, are effective photocatalysts for the degradation of monochlorophenols (MCPs: 2-CP, 3-CP, and 4-CP) which are prominent water contaminants. The removal efficiency of 2-CP and 4-CP reached 87% and 64%, respectively, after treatment of 25 ppm CP solutions with the photocatalyst (40TiO₂/g-C₃N₄, 1 g/L) and irradiation with UV–Vis light. Treatment of CP solutions with g-C₃N₄ nanosheets or TiO₂ alone in conjunction with irradiation gave removal efficiencies lower than 50%, which suggests the two act synergically to enhance the photocatalytic activity of the 40TiO₂/g-C₃N₄ nanocomposite. Superoxide and hydroxyl radicals are key active species produced during CP photodegradation. In addition, the observed nitrogen and Ti³⁺ defects and oxygen vacancies in the TiO₂/g-C₃N₄ nanocomposites may improve the light-harvesting ability of the composite and assist preventing rapid electron-hole recombination on the surface, enhancing the photocatalytic performance. In addition, interfacial interactions between the MCPs (low polarity) and thermally exfoliated carbon nitride in the TiO₂/g-C₃N₄ nanocomposites may also enhance MCP degradation. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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10 pages, 666 KiB

Open AccessArticle

Charge Transport in UV-Oxidized Graphene and Its Dependence on the Extent of Oxidation

by Hwa Yong Lee, Mohd Musaib Haidari, Eun Hee Kee, Jin Sik Choi, Bae Ho Park, Eleanor E. B. Campbell and Sung Ho Jhang

Nanomaterials 2022, 12(16), 2845; https://doi.org/10.3390/nano12162845 - 18 Aug 2022

Cited by 1 | Viewed by 1267

Abstract

Graphene oxides with different degrees of oxidation are prepared by controlling UV irradiation on graphene, and the charge transport and the evolution of the transport gap are investigated according to the extent of oxidation. With increasing oxygenous defect density

n_{D}

, a [...] Read more.

Graphene oxides with different degrees of oxidation are prepared by controlling UV irradiation on graphene, and the charge transport and the evolution of the transport gap are investigated according to the extent of oxidation. With increasing oxygenous defect density

n_{D}

, a transition from ballistic to diffusive conduction occurs at

n_{D} ≃ 10^{12}

cm

^{- 2}

and the transport gap grows in proportion to

\sqrt{n_{D}}

. Considering the potential fluctuation related to the

e - h

puddle, the bandgap of graphene oxide is deduced to be

E_{g} ≃ 30 \sqrt{n_{D} (10^{12} {cm}^{- 2})}

meV. The temperature dependence of conductivity showed metal–insulator transitions at

n_{D} ≃ 0.3 \times 10^{12}

cm

^{- 2}

, consistent with Ioffe–Regel criterion. For graphene oxides at

n_{D} \geq 4.9 \times 10^{12}

cm

^{- 2}

, analysis indicated charge transport occurred via 2D variable range hopping conduction between localized

s p^{2}

domain. Our work elucidates the transport mechanism at different extents of oxidation and supports the possibility of adjusting the bandgap with oxygen content. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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12 pages, 2906 KiB

Open AccessArticle

The Effect of Annealing and Optical Radiation Treatment on Graphene Resonators

by Yujian Liu, Cheng Li, Shangchun Fan, Xuefeng Song and Zhen Wan

Nanomaterials 2022, 12(15), 2725; https://doi.org/10.3390/nano12152725 - 08 Aug 2022

Cited by 5 | Viewed by 1384

Abstract

Graphene resonant sensors have shown strong competitiveness with respect to sensitivity and size. To advance the applications of graphene resonant sensors, the damage behaviors of graphene harmonic oscillators after thermal annealing and laser irradiation were investigated by morphology analysis and frequency domain vibration [...] Read more.

Graphene resonant sensors have shown strong competitiveness with respect to sensitivity and size. To advance the applications of graphene resonant sensors, the damage behaviors of graphene harmonic oscillators after thermal annealing and laser irradiation were investigated by morphology analysis and frequency domain vibration characteristics. The interface stress was proven to be the key factor that directly affected the yield of resonators. The resulting phenomenon could be improved by appropriately controlling the annealing temperature and size of resonators, thereby achieving membrane intactness of up to 96.4%. However, micro-cracks were found on the graphene sheets when continuous wave (CW) laser power was more than 4 mW. Moreover, the fluctuating light energy would also cause mechanical fatigue in addition to the photothermal effect, and the threshold damage power for the sinusoidally modulated laser was merely 2 mW. In this way, based on the amplitude-frequency surface morphology of the graphene resonator, the thermal time constant of the order of a few microseconds was confirmed to evaluate the damage of the graphene oscillator in situ and in real time, which could be further extended for those resonators using other 2D materials. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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16 pages, 1747 KiB

Open AccessArticle

Photothermal Responsivity of van der Waals Material-Based Nanomechanical Resonators

by Myrron Albert Callera Aguila, Joshoua Condicion Esmenda, Jyh-Yang Wang, Yen-Chun Chen, Teik-Hui Lee, Chi-Yuan Yang, Kung-Hsuan Lin, Kuei-Shu Chang-Liao, Sergey Kafanov, Yuri A. Pashkin and Chii-Dong Chen

Nanomaterials 2022, 12(15), 2675; https://doi.org/10.3390/nano12152675 - 04 Aug 2022

Viewed by 1757

Abstract

Nanomechanical resonators made from van der Waals materials (vdW NMRs) provide a new tool for sensing absorbed laser power. The photothermal response of vdW NMRs, quantified from the resonant frequency shifts induced by optical absorption, is enhanced when incorporated in a Fabry–Pérot (FP) [...] Read more.

Nanomechanical resonators made from van der Waals materials (vdW NMRs) provide a new tool for sensing absorbed laser power. The photothermal response of vdW NMRs, quantified from the resonant frequency shifts induced by optical absorption, is enhanced when incorporated in a Fabry–Pérot (FP) interferometer. Along with the enhancement comes the dependence of the photothermal response on NMR displacement, which lacks investigation. Here, we address the knowledge gap by studying electromotively driven niobium diselenide drumheads fabricated on highly reflective substrates. We use a FP-mediated absorptive heating model to explain the measured variations of the photothermal response. The model predicts a higher magnitude and tuning range of photothermal responses on few-layer and monolayer NbSe₂ drumheads, which outperform other clamped vdW drum-type NMRs at a laser wavelength of 532 nm. Further analysis of the model shows that both the magnitude and tuning range of NbSe₂ drumheads scale with thickness, establishing a displacement-based framework for building bolometers using FP-mediated vdW NMRs. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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16 pages, 6280 KiB

Open AccessArticle

Ag–Se/Nylon Nanocomposites Grown by Template-Engaged Reaction: Microstructures, Composition, and Optical Properties

by Valentina Krylova, Nijolė Dukštienė and Henrieta Markevičiūtė

Nanomaterials 2022, 12(15), 2584; https://doi.org/10.3390/nano12152584 - 27 Jul 2022

Viewed by 1255

Abstract

Ag–Se nanostructure films were deposited on a–Se/nylon templates by a template-engaged reaction. Firstly, amorphous selenium (a–Se) was deposited on nylon by employing the chemical bath deposition method while using H₂SeO₃ and Na₂SO₃ solutions with an increasing selenium [...] Read more.

Ag–Se nanostructure films were deposited on a–Se/nylon templates by a template-engaged reaction. Firstly, amorphous selenium (a–Se) was deposited on nylon by employing the chemical bath deposition method while using H₂SeO₃ and Na₂SO₃ solutions with an increasing selenium deposition time. Then, these a–Se/nylon templates were exposed into AgNO₃ solution at ambient temperature and pressure. The Ag–Se/nylon nanocomposites surface morphology, elemental and phase composition, and optical properties were monitored depending on the selenium deposition time on nylon. Scanning electron microscopy (SEM) analysis confirmed the development of a very complex surface composed of pyramidal-like sub-micron structures, agglomerates, and grid-like structures. Energy dispersive spectroscopy (EDS) proved the presence of carbon, oxygen, nitrogen, selenium, and silver. SEM/EDS cross-sectional analysis confirmed the multilayer character with different individual elemental composition in each film layer. X-ray diffraction analysis revealed a polycrystalline Ag₂Se phase with or without metallic Ag. The RMS value obtained from atomic force microscopy varies from 25.82 nm to 57.04 nm. From the UV-Vis spectrophotometry, the direct optical band gaps were found to be 1.68–1.86 eV. Ag–Se/nylon composites exhibit high refractive indices in the near infrared region. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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18 pages, 5199 KiB

Open AccessArticle

A Novel Electrochemical Sensor for Detection of Nicotine in Tobacco Products Based on Graphene Oxide Nanosheets Conjugated with (1,2-Naphthoquinone-4-Sulphonic Acid) Modified Glassy Carbon Electrode

by M. Abd-Elsabour, Hesham M. Alsoghier, Abdulrahman G. Alhamzani, Mortaga M. Abou-Krisha, Tarek A. Yousef and Hytham F. Assaf

Nanomaterials 2022, 12(14), 2354; https://doi.org/10.3390/nano12142354 - 09 Jul 2022

Cited by 5 | Viewed by 1921

Abstract

A simple electrochemical sensor for nicotine (NIC) detection was performed. The sensor based on a glassy carbon electrode (GCE) was modified by (1,2-naphthoquinone-4-sulphonic acid)(Nq) decorated by graphene oxide (GO) nanocomposite. The synthesized (GO) nanosheets were characterized using X-ray diffraction (XRD), Raman spectroscopy, scanning [...] Read more.

A simple electrochemical sensor for nicotine (NIC) detection was performed. The sensor based on a glassy carbon electrode (GCE) was modified by (1,2-naphthoquinone-4-sulphonic acid)(Nq) decorated by graphene oxide (GO) nanocomposite. The synthesized (GO) nanosheets were characterized using X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscope (SEM), transmission electron microscope (TEM), FT-IR, and UV-Visible Spectroscopy. The insertion of Nq with GO nanosheets on the surface of GCE displayed high electrocatalytic activity towards NIC compared to the bare GCE. NIC determination was performed under the optimum conditions using 0.10 M of Na₂SO₄ as a supporting electrolyte with pH 8.0 at a scan rate of 100 mV/s using both cyclic voltammetry (CV) and differential pulse voltammetry (DPV). This electrochemical sensor showed an excellent result for NIC detection. The oxidation peak current increased linearly with a 6.5–245 µM of NIC with R² = 0.9999. The limit of detection was 12.7 nM. The fabricated electrode provided satisfactory stability, reproducibility, and selectivity for NIC oxidation. The reliable GO/Nq/GCE sensor was successfully applied for detecting NIC in the tobacco product and a urine sample. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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12 pages, 17526 KiB

Open AccessEditor’s ChoiceArticle

Performance Enhancement of SPR Biosensor Using Graphene–MoS₂ Hybrid Structure

by Haoyuan Cai, Mengwei Wang, Zhuohui Wu, Jing Liu and Xiaoping Wang

Nanomaterials 2022, 12(13), 2219; https://doi.org/10.3390/nano12132219 - 28 Jun 2022

Cited by 11 | Viewed by 2152

Abstract

We investigate a high-sensitivity surface plasmon resonance (SPR) biosensor consisting of a Au layer, four-layer MoS₂, and monolayer graphene. The numerical simulations, by the transfer matrix method (TMM), demonstrate the sensor has a maximum sensitivity of 282°/RIU, which is approximately 2 [...] Read more.

We investigate a high-sensitivity surface plasmon resonance (SPR) biosensor consisting of a Au layer, four-layer MoS₂, and monolayer graphene. The numerical simulations, by the transfer matrix method (TMM), demonstrate the sensor has a maximum sensitivity of 282°/RIU, which is approximately 2 times greater than the conventional Au-based SPR sensor. The finite difference time domain (FDTD) indicates that the presence of MoS₂ film generates a strong surface electric field and enhances the sensitivity of the proposed SPR sensor. In addition, the influence of the number of MoS₂ layers on the sensitivity of the proposed sensor is investigated by simulations and experiments. In the experiment, MoS₂ and graphene films are transferred on the Au-based substrate by the PMMA-based wet transfer method, and the fabricated samples are characterized by Raman spectroscopy. Furthermore, the fabricated sensors with the Kretschmann configuration are used to detect okadaic acid (OA). The okadaic acid–bovine serum albumin bioconjugate (OA-BSA) is immobilized on the graphene layer of the sensors to develop a competitive inhibition immunoassay. The results show that the sensor has a very low limit of detection (LOD) of 1.18 ng/mL for OA, which is about 22.6 times lower than that of a conventional Au biosensor. We believe that such a high-sensitivity SPR biosensor has potential applications for clinical diagnosis and immunoassays. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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15 pages, 5487 KiB

Open AccessArticle

Pulsed Fluidization of Nanosilica: Rigorous Evaluation of the Efficacy of Pulsation Frequency

by Mohammad Asif, Ebrahim H. Al-Ghurabi and Amanullah Fatehmulla

Nanomaterials 2022, 12(13), 2158; https://doi.org/10.3390/nano12132158 - 23 Jun 2022

Viewed by 1078

Abstract

Assisted fluidization techniques can significantly improve the hydrodynamics of difficult- to-fluidize solids. Among these techniques, the pulsed flow strategy is highly promising owing to its cost-effectiveness and amenability to implementation for largescale processing. Using commercial-grade, highly porous nanosilica that shows strong agglomeration behavior, [...] Read more.

Assisted fluidization techniques can significantly improve the hydrodynamics of difficult- to-fluidize solids. Among these techniques, the pulsed flow strategy is highly promising owing to its cost-effectiveness and amenability to implementation for largescale processing. Using commercial-grade, highly porous nanosilica that shows strong agglomeration behavior, we implemented the pulsed flow with square-wave pulsation schemes of 0.05, 0.10, and 0.25 Hz frequencies, and compared their effectiveness in each case. Besides the conventional approach of assessing their efficacy using the pressure drop data, we have proposed a new approach in this work that consists of computing the power of the overall pressure drop transient signals. Using the theoretical value, i.e., the effective bed weight per unit area as a reference, the percentage increase in the power was 27 ± 4, 71 ± 5, and 128 ± 4, respectively, for 0.05, 0.10, and 0.25 Hz pulsation frequencies. In fact, the average pressure drop values were substantially higher when the partial bed collapse occurred between successive pulsations when compared with the case of low-frequency pulsations. The pulsation frequency also affected the evolution of local bed dynamics in various bed regions during the expansion and collapse of the bed. Moreover, the local and global pressure transients have shown interesting mutual correlations which were otherwise not evident from their individual transient profiles. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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18 pages, 6712 KiB

Open AccessArticle

Enhancing the Low-Temperature CO Oxidation over CuO-Based α-MnO₂ Nanowire Catalysts

by Yan Cui, Huikang Song, Yiyu Shi, Pengxiang Ge, Mindong Chen and Leilei Xu

Nanomaterials 2022, 12(12), 2083; https://doi.org/10.3390/nano12122083 - 16 Jun 2022

Cited by 6 | Viewed by 1628

Abstract

A series of CuO-based catalysts supported on the α-MnO₂ nanowire were facilely synthesized and employed as the CO oxidation catalysts. The achieved catalysts were systematically characterized by XRD, SEM, EDS-mapping, XPS and H₂-TPR. The catalytic performances toward CO oxidation had [...] Read more.

A series of CuO-based catalysts supported on the α-MnO₂ nanowire were facilely synthesized and employed as the CO oxidation catalysts. The achieved catalysts were systematically characterized by XRD, SEM, EDS-mapping, XPS and H₂-TPR. The catalytic performances toward CO oxidation had been carefully evaluated over these CuO-based catalysts. The effects of different loading methods, calcination temperatures and CuO loading on the low temperature catalytic activity of the catalyst were investigated and compared with the traditional commercial MnO₂ catalyst with a block structure. It was found that the slenderness ratio of a CuO/α-MnO₂ nanowire catalyst decreases with the increase in CuO loading capacity. The results showed that when CuO loading was 3 wt%, calcination temperature was 200 °C and the catalyst that was supported by the deposition precipitation method had the highest catalytic activity. Besides, the α-MnO₂ nanowire-supported catalysts with excellent redox properties displayed much better catalytic performances than the commercial MnO₂-supported catalyst. In conclusion, the CuO-based catalysts that are supported by α-MnO₂ nanowires are considered as a series of promising CO oxidation catalysts. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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12 pages, 4030 KiB

Open AccessArticle

Atomistic Insights into the Phase Transformation of Single-Crystal Silicon during Nanoindentation

by Young Jin Chung, Gi Hun Lee and Hyeon Gyu Beom

Nanomaterials 2022, 12(12), 2071; https://doi.org/10.3390/nano12122071 - 16 Jun 2022

Cited by 1 | Viewed by 1671

Abstract

The influence of the indenter angle on the deformation mechanisms of single-crystal Si was analyzed via molecular dynamics simulations of the nanoindentation process. Three different types of diamond conical indenters with semi-angles of 45°, 60°, and 70° were used. The load–indentation depth curves [...] Read more.

The influence of the indenter angle on the deformation mechanisms of single-crystal Si was analyzed via molecular dynamics simulations of the nanoindentation process. Three different types of diamond conical indenters with semi-angles of 45°, 60°, and 70° were used. The load–indentation depth curves were obtained by varying the indenter angles, and the structural phase transformations of single-crystal Si were observed from an atomistic view. In addition, the hardness and elastic modulus with varying indenter angles were evaluated based on the Oliver–Pharr method and Sneddon’s solution. The simulation results showed that the indenter angle had a significant effect on the load–indentation depth curves, which resulted from the strong dependence of the elastic and plastic deformation ratios on the indenter angle during indentations. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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21 pages, 7393 KiB

Open AccessArticle

Effect of Voidage on the Collapsing Bed Dynamics of Fine Particles: A Detailed Region-Wise Study

by Syed Sadiq Ali, Agus Arsad, Kenneth L. Roberts and Mohammad Asif

Nanomaterials 2022, 12(12), 2019; https://doi.org/10.3390/nano12122019 - 11 Jun 2022

Cited by 2 | Viewed by 1333

Abstract

Bed collapse experiments provide vital information about fluidized bed hydrodynamics. In this study, the region-wise bed collapse dynamics of glass beads, titania (TiO₂), and hydrophilic nanosilica (SiO₂) particles with widely different voidages (ε) of 0.38, 0.80, and 0.98, respectively, [...] Read more.

Bed collapse experiments provide vital information about fluidized bed hydrodynamics. In this study, the region-wise bed collapse dynamics of glass beads, titania (TiO₂), and hydrophilic nanosilica (SiO₂) particles with widely different voidages (ε) of 0.38, 0.80, and 0.98, respectively, were carefully investigated. These particles belonged to different Geldart groups and exhibited varied hysteresis phenomena and fluidization indices. The local collapse dynamics in the lower, lower-middle, upper-middle, and upper regions were carefully monitored in addition to the distributor pressure drop to obtain greater insight into the deaeration behavior of the bed. While the collapse dynamics of glass beads revealed high bed homogeneity, the upper middle region controlled the collapse process in the case of titania due to the size-based segregation along the bed height. The segregation behavior was very strong for nanosilica, with the slow settling fine agglomerates in the upper bed regions controlling its collapse dynamics. The collapse time of the upper region was 25 times slower than that of the lower region containing mainly large agglomerates. The spectral analysis confirmed the trend that was observed in the pressure transients. The clear presence of high frequency events at 20 and 40 Hz was observed in the nanosilica due to agglomerate movements. The residual air exiting the plenum was strongly affected by the bed voidage, being lowest for the nanosilica and highest for the glass beads. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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19 pages, 15798 KiB

Open AccessArticle

New Approach for Designing Zinc Oxide Nanohybrids to Be Effective Photocatalysts for Water Purification in Sunlight

by Osama Saber, Aya Osama, Adil Alshoaibi, Nagih M. Shaalan and Doaa Osama

Nanomaterials 2022, 12(12), 2005; https://doi.org/10.3390/nano12122005 - 10 Jun 2022

Cited by 2 | Viewed by 1366

Abstract

Water pollution and deficient energy are the main challenges for the scientific society across the world. In this trend, new approaches include designing zinc oxide nanohybrids to be very active in sunlight. In this line, organic and magnetic species intercalate among the nanolayers [...] Read more.

Water pollution and deficient energy are the main challenges for the scientific society across the world. In this trend, new approaches include designing zinc oxide nanohybrids to be very active in sunlight. In this line, organic and magnetic species intercalate among the nanolayers of Al/Zn to build inorganic-magnetic-organic nanohybrid structures. A series of nanolayered and nanohybrid structures have been prepared through intercalating very fine particles of cobalt iron oxide nanocomposites and long chains of organic fatty acids such as n-capric acid and stearic acid inside the nanolayered structures of Al/Zn. By thermal treatment, zinc oxide nanohybrids have been prepared and used for purifying water from colored pollutants using solar energy. The optical measurements have shown that the nanohybrid structure of zinc oxide leads to a clear reduction of band gap energy from 3.30 eV to 2.60 eV to be effective in sunlight. In this line, a complete removal of the colored pollutants (naphthol green B) was achieved after ten minutes in the presence of zinc oxide nanohybrid and sunlight. Finally, this new approach for designing photoactive nanohybrids leads to positive results for facing the energy- and water-related problems through using renewable and non-polluting energy for purifying water. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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15 pages, 4270 KiB

Open AccessArticle

Role of Ambient Hydrogen in HiPIMS-ITO Film during Annealing Process in a Large Temperature Range

by Ming-Jie Zhao, Jin-Fa Zhang, Jie Huang, Zuo-Zhu Chen, An Xie, Wan-Yu Wu, Chien-Jung Huang, Dong-Sing Wuu, Shui-Yang Lien and Wen-Zhang Zhu

Nanomaterials 2022, 12(12), 1995; https://doi.org/10.3390/nano12121995 - 10 Jun 2022

Viewed by 1533

Abstract

Indium tin oxide (ITO) thin films were prepared by high power impulse magnetron sputtering (HiPIMS) and annealed in hydrogen-containing forming gas to reduce the film resistivity. The film resistivity reduces by nearly an order of magnitude from 5.6 × 10⁻³ Ω·cm for [...] Read more.

Indium tin oxide (ITO) thin films were prepared by high power impulse magnetron sputtering (HiPIMS) and annealed in hydrogen-containing forming gas to reduce the film resistivity. The film resistivity reduces by nearly an order of magnitude from 5.6 × 10⁻³ Ω·cm for the as-deposited film to the lowest value of 6.7 × 10⁻⁴ Ω·cm after annealed at 700 °C for 40 min. The role of hydrogen (H) in changing the film properties was explored and discussed in a large temperature range (300–800 °C). When annealed at a low temperature of 300–500 °C, the incorporated H atoms occupied the oxygen sites (H_o), acting as shallow donors that contribute to the increase of carrier concentration, leading to the decrease of film resistivity. When annealed at an intermediate temperature of 500–700 °C, the H_o defects are thermally unstable and decay upon annealing, leading to the reduction of carrier concentration. However, the film resistivity keeps decreasing due to the increase in carrier mobility. Meanwhile, some locally distributed metallic clusters formed due to the reduction effect of H₂. When annealed at a high temperature of 700–800 °C, the metal oxide film is severely reduced and transforms to gaseous metal hydride, leading to the dramatic reduction of film thickness and carrier mobility at 750 °C and vanish of the film at 800 °C. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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14 pages, 6363 KiB

Open AccessArticle

Nanohollow Titanium Oxide Structures on Ti/FTO Glass Formed by Step-Bias Anodic Oxidation for Photoelectrochemical Enhancement

by Chi-Hsien Huang, Yu-Jen Lu, Yong-Chen Pan, Hui-Ling Liu, Jia-Yuan Chang, Jhao-Liang Sie, Dorota G. Pijanowska and Chia-Ming Yang

Nanomaterials 2022, 12(11), 1925; https://doi.org/10.3390/nano12111925 - 04 Jun 2022

Cited by 2 | Viewed by 1626

Abstract

In this study, a new anodic oxidation with a step-bias increment is proposed to evaluate oxidized titanium (Ti) nanostructures on transparent fluorine-doped tin oxide (FTO) on glass. The optimal Ti thickness was determined to be 130 nm. Compared to the use of a [...] Read more.

In this study, a new anodic oxidation with a step-bias increment is proposed to evaluate oxidized titanium (Ti) nanostructures on transparent fluorine-doped tin oxide (FTO) on glass. The optimal Ti thickness was determined to be 130 nm. Compared to the use of a conventional constant bias of 25 V, a bias ranging from 5 V to 20 V with a step size of 5 V for 3 min per period can be used to prepare a titanium oxide (TiO_x) layer with nanohollows that shows a large increase in current of 142% under UV illumination provided by a 365 nm LED at a power of 83 mW. Based on AFM and SEM, the TiO_x grains formed in the step-bias anodic oxidation were found to lead to nanohollow generation. Results obtained from EDS mapping, HR-TEM and XPS all verified the TiO_x composition and supported nanohollow formation. The nanohollows formed in a thin TiO_x layer can lead to a high surface roughness and photon absorbance for photocurrent generation. With this step-bias anodic oxidation methodology, TiO_x with nanohollows can be obtained easily without any extra cost for realizing a high current under photoelectrochemical measurements that shows potential for electrochemical-based sensing applications. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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14 pages, 5632 KiB

Open AccessEditor’s ChoiceArticle

Effectiveness of Oxygen during Sintering of Silver Thin Films Derived by Nanoparticle Ink

by Feng Feng, Haofeng Hong, Xing Gao, Tian Ren, Yuan Ma and Pingfa Feng

Nanomaterials 2022, 12(11), 1908; https://doi.org/10.3390/nano12111908 - 02 Jun 2022

Cited by 4 | Viewed by 1892

Abstract

Silver nanoparticle (NP) inks have been widely used in the ink-jet printing field because of their excellent properties during low-temperature sintering. However, the organic dispersant used to prevent the aggregation and sedimentation of NPs can hinder the sintering process and result in the [...] Read more.

Silver nanoparticle (NP) inks have been widely used in the ink-jet printing field because of their excellent properties during low-temperature sintering. However, the organic dispersant used to prevent the aggregation and sedimentation of NPs can hinder the sintering process and result in the high resistivity of sintered films. In this study, silver thin films derived from silver NP ink with polyvinylpyrrolidone (PVP) dispersant were sintered in different atmospheres of pure nitrogen, air, and pure oxygen. The effect of the oxygen content in the sintering atmosphere on the thermal properties of the ink, the electrical resistivity and microstructure of the sintered films, and the amount of organic residue were studied by using differential scanning calorimetry, the four-point probe method, scanning electron microscopy, Fourier transform infrared spectroscopy, etc. The mechanism of optimizing the film resistivity by influencing the decomposition of the PVP dispersant and the microstructure evolution of the silver thin films through the sintering atmosphere was discussed. The results demonstrated that an oxygen-containing atmosphere could be effective for silver NPs in two ways. First, the oxygen content could enhance the diffusion ability of silver atoms, thus accelerating the stage transition of microstructural evolution at low temperatures. Second, the oxygen content could enable the PVP to decompose at a temperature much lower than in conditions of pure nitrogen, thus helping to finalize the densification of a silver film with a low resistivity of 2.47 μΩ·cm, which is approximately 1.5-fold that of bulk silver. Our findings could serve as a foundation for the subsequent establishment of ink-jet printing equipment and the optimization of the sintering process for printing silver patterns on flexible substrates. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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12 pages, 2666 KiB

Open AccessArticle

Polarization Sensitive Photodetectors Based on Two-Dimensional WSe₂

by Andrey Guskov, Sergey Lavrov and Rinat Galiev

Nanomaterials 2022, 12(11), 1854; https://doi.org/10.3390/nano12111854 - 29 May 2022

Cited by 3 | Viewed by 1952

Abstract

In this work we show the possibility of imparting polarization-sensitive properties to two-dimensional films of graphene-like semiconductors, using WSe₂ as an example, by the application of ordered silver triangular nanoprisms. In addition, such nanoprisms made it possible to increase the optical sensitivity [...] Read more.

In this work we show the possibility of imparting polarization-sensitive properties to two-dimensional films of graphene-like semiconductors, using WSe₂ as an example, by the application of ordered silver triangular nanoprisms. In addition, such nanoprisms made it possible to increase the optical sensitivity of optical detectors created on two-dimensional films by a factor of five due to surface plasmon resonance. The peculiarities of the surface plasmon resonance were shown by theoretical modeling, and the optimal conditions of its occurrence were determined. This article demonstrates an effective approach to creating spectrally selective, polarization-sensitive detectors based on two-dimensional graphene-like semiconductors. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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12 pages, 2727 KiB

Open AccessArticle

Development of Electrolyzer Using NiCo(OH)₂ Layered Double Hydroxide Catalyst for Efficient Water Oxidation Reaction

by Rafia Nimal, Rashida Yahya, Afzal Shah, Muhammad Abdullah Khan, Muhammad Abid Zia and Iltaf Shah

Nanomaterials 2022, 12(11), 1819; https://doi.org/10.3390/nano12111819 - 26 May 2022

Cited by 4 | Viewed by 1872

Abstract

Over the past decade, layered double hydroxides (LDH) have been the subject of extensive investigations owing to their remarkable water splitting catalytic activity. Stability and porosity are several of the features of LDH which help them to serve as efficient oxygen evolution reaction [...] Read more.

Over the past decade, layered double hydroxides (LDH) have been the subject of extensive investigations owing to their remarkable water splitting catalytic activity. Stability and porosity are several of the features of LDH which help them to serve as efficient oxygen evolution reaction (OER) catalysts. Based on these considerations, we synthesized NiCo(OH)₂ LDH and probed its OER electrocatalytic performance. The synthesized catalyst was subjected to X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy for structural analysis and investigation of its surface morphology, surface composition, and oxidation states. The LDH-NiCo(OH)₂ was anchored over the FTO surface and the fabricated electrode was found to exhibit a much lower OER onset potential of 265 mV, a much higher current density of 300 mAcm⁻² and a smaller Tafel slope of 41 mVdec⁻¹. Moreover, the designed catalyst was found to be stable up to 2500 repeated voltametric scans. These figures of merit regarding the structure and performance of the designed LDH are expected to provide useful insights into the fundamental understanding of the OER catalysts and their mechanisms of action, thus enabling the more rational design of cost effective and highly efficient electrocatalysts for use in water splitting. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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12 pages, 3572 KiB

Open AccessArticle

Tunable Switching Behavior of GO-Based Memristors Using Thermal Reduction

by Muayad Abujabal, Heba Abunahla, Baker Mohammad and Anas Alazzam

Nanomaterials 2022, 12(11), 1812; https://doi.org/10.3390/nano12111812 - 25 May 2022

Cited by 9 | Viewed by 1684

Abstract

This work reports on the fabrication of a novel planar reduced graphene oxide (rGO) memristor (MR) device. For the first time in the literature, the MR tunable resistive switching behavior is controlled by the GO reduction time at a constant temperature. The device [...] Read more.

This work reports on the fabrication of a novel planar reduced graphene oxide (rGO) memristor (MR) device. For the first time in the literature, the MR tunable resistive switching behavior is controlled by the GO reduction time at a constant temperature. The device is fabricated using standard microfabrication techniques on a flexible cyclic olefin copolymer substrate (COC). Thermal reduction of the GO layer at low temperatures (100 °C) avoids the drawbacks of chemical reduction methods such as toxicity and electrode metal damage during fabrication, while allowing for fine-tuning of the MR’s switching behavior. The device has analog switching characteristics, with a range of different resistance states. By taking advantage of the slow nature of GO thermal annealing, the switching properties of the rGO memristors can be precisely controlled by adjusting the reduction period. At short annealing times (i.e., T < 20 h), the devices switch from high to low resistance states, while at longer annealing times the switching behavior is reversed, with the device switching from low to high resistance states (LRS to HRS). Resistive switching occurs as a result of the diffusion and removal of the oxygen functional groups in the GO film caused by Joule heating induced by the electric current. Complete electrical characterization tests are presented along with wettability and X-ray diffraction (XRD) tests. This work opens a new vision for realizing rGO-based MR devices with tunable switching properties, broadening the application horizon of the device. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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7 pages, 2098 KiB

Open AccessArticle

A Simple Grinding Method for Preparing Ultra-Thin Boron Nanosheets

by Haoran Wang, Zuxin Sun, Zuoshan Wei and Yuying Wu

Nanomaterials 2022, 12(11), 1784; https://doi.org/10.3390/nano12111784 - 24 May 2022

Viewed by 1504

Abstract

The preparation of boron nanosheets has very strict requirements of the preparation environment and substrate. In this work, the boron nanosheets were tried to prepare by the grinding method, using β-B alloy with stable chemical properties and large crystal plane spacing. Its morphology [...] Read more.

The preparation of boron nanosheets has very strict requirements of the preparation environment and substrate. In this work, the boron nanosheets were tried to prepare by the grinding method, using β-B alloy with stable chemical properties and large crystal plane spacing. Its morphology and chemical bonds of boron nanosheets were analyzed by scanning microscope (SEM), transmission microscope (TEM), and X-ray photoelectron spectroscopy (XPS). The results show that the two-dimensional boron nanosheets can be prepared from β-B powder by the grinding method. There are very few B-O bonds in boron particles, and the B-B bonds are principally dominant. In addition to a few B-O bonds, including some B-B bonds change to B₆O bonds which are not completely oxidized, indicating that boron has certain oxidation resistance. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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12 pages, 4225 KiB

Open AccessArticle

Theoretical Study on Electronic, Magnetic and Optical Properties of Non-Metal Atoms Adsorbed onto Germanium Carbide

by Lin Zhang and Zhen Cui

Nanomaterials 2022, 12(10), 1712; https://doi.org/10.3390/nano12101712 - 17 May 2022

Cited by 20 | Viewed by 1849

Abstract

Nine kinds of non-metal atoms adsorbed into germanium carbide (NM-GeC) systems wereare investigated by first-principles calculations. The results show that the most stable adsorption positions vary with the NM atoms, and C-GeC exhibits the strongest adsorption. The adsorption of NM atoms causes changes [...] Read more.

Nine kinds of non-metal atoms adsorbed into germanium carbide (NM-GeC) systems wereare investigated by first-principles calculations. The results show that the most stable adsorption positions vary with the NM atoms, and C-GeC exhibits the strongest adsorption. The adsorption of NM atoms causes changes in the electronic, optical and magnetic properties of the GeC system. F- and Cl-GeC turn into magnetic metals, P-GeC becomes a half-metal and H- and B-GeC appear as non-magnetic metals. Although C- and O-GeC remain non-magnetic semiconductors, N-GeC presents the behaviors of a magnetic semiconductor. Work function decreases in H-, B- and N-SiC, reaching a minimum of 3.37 eV in H-GeC, which is 78.9% of the pristine GeC. In the visible light region, redshifts occur in the absorption spectrum of C-GeC , with strong absorption in the wavelength range from 400 to 600 nm. Our analysis shows that the magnetism in semiconducting NM-GeC is attributed to the spinning state of the unbonded electrons of the NM atoms. Our study demonstrates the applications of NM-GeC in spintronics, optoelectronics and photovoltaic cells, and it provides a reference for analyzing magnetism in semiconducting NM materials. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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9 pages, 2399 KiB

Open AccessArticle

Variations in the Physical Properties of RF-Sputtered CdS Thin Films Observed at Substrate Temperatures Ranging from 25 °C to 500 °C

by Sangwoon Lee, Juna Kim, Seokhee Lee, Hyun-Jin Cha, Chang-Sik Son, Young-Guk Son and Donghyun Hwang

Nanomaterials 2022, 12(10), 1618; https://doi.org/10.3390/nano12101618 - 10 May 2022

Cited by 5 | Viewed by 1279

Abstract

CdS films with a wide range of substrate temperatures as deposition parameters were fabricated on Corning Eagle 2000 glass substrates using RF magnetron sputtering. The crystallographic structure, microscopic surface texture, and stoichiometric and optical properties of each CdS film deposited at various substrate [...] Read more.

CdS films with a wide range of substrate temperatures as deposition parameters were fabricated on Corning Eagle 2000 glass substrates using RF magnetron sputtering. The crystallographic structure, microscopic surface texture, and stoichiometric and optical properties of each CdS film deposited at various substrate temperatures were observed to be highly temperature-dependent. The grown CdS thin films revealed a polycrystalline structure in which a cubic phase was mixed based on a hexagonal wurtzite phase. The relative intensity of the H(002)/C(111) peak, which represents the direction of the preferential growth plane, enhanced as the temperatures climbed from 25 °C to 350 °C. On the contrary, the intensity of the main growth peak at the higher temperatures of 450 °C and 500 °C was significantly reduced and exhibited amorphous-like behavior. The sharp absorption edge revealed in the transmission spectrum shifted from the long wavelength to the short wavelength region with the rise in the substrate temperature. The bandgap showed a tendency to widen from 2.38 eV to 2.97 eV when the temperatures increased from 25 °C to 350 °C. The CdS films grown at the temperatures of 450 °C and 500 °C exhibited glass-like transmittance with almost no interference fringes of light, which resulted in wide bandgap values of 3.09 eV and 4.19 eV, respectively. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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22 pages, 4771 KiB

Open AccessArticle

A Detailed Insight into Acoustic Attenuation in a Static Bed of Hydrophilic Nanosilica

by Syed Sadiq Ali, Agus Arsad, SK Safdar Hossain and Mohammad Asif

Nanomaterials 2022, 12(9), 1509; https://doi.org/10.3390/nano12091509 - 28 Apr 2022

Cited by 3 | Viewed by 1436

Abstract

The commercial utilization of bulk nanosilica is widespread in concrete, rubber and plastics, cosmetics and agriculture-related applications, and the market of this product is projected to exceed USD 5 billion by 2025. In this investigation, the local dynamics of a nanosilica bed, excited [...] Read more.

The commercial utilization of bulk nanosilica is widespread in concrete, rubber and plastics, cosmetics and agriculture-related applications, and the market of this product is projected to exceed USD 5 billion by 2025. In this investigation, the local dynamics of a nanosilica bed, excited with sinusoidal acoustic waves of different frequencies, were carefully monitored using sensitive pressure transducers to obtain detailed insights into the effectiveness of sound waves as a means of energy transport inside the bed. The evolution of wave patterns and their frequency and power distributions were examined both in the freeboard and in the static bed. These results were compared with those obtained by using an empty column. The acoustic frequency strongly affected the signal power. The average power of the acoustic signal in the freeboard region was twice higher than that for the empty column, whereas the same (power) ratio decreased to approximately 0.03 inside the bed for 300 Hz. However, at 360 Hz, the power ratio was substantially lower at 0.24 and 0.002 for the freeboard and the granular bed, respectively, thereby indicating tremendous attenuation of acoustic waves in the granular media at all frequencies. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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15 pages, 2582 KiB

Open AccessArticle

One-Dimensional Nanoscale Si/Co Based on Layered Double Hydroxides towards Electrochemical Supercapacitor Electrodes

by Osama Saber, Sajid Ali Ansari, Aya Osama and Mostafa Osama

Nanomaterials 2022, 12(9), 1404; https://doi.org/10.3390/nano12091404 - 20 Apr 2022

Cited by 5 | Viewed by 1607

Abstract

It is well known that layered double hydroxides (LDHs) are two-dimensional (2D) layered compounds. However, we modified these 2D layered compounds to become one-dimensional (1D) nanostructures destined for high-performance supercapacitors applications. In this direction, silicon was inserted inside the nanolayers of Co-LDHs producing [...] Read more.

It is well known that layered double hydroxides (LDHs) are two-dimensional (2D) layered compounds. However, we modified these 2D layered compounds to become one-dimensional (1D) nanostructures destined for high-performance supercapacitors applications. In this direction, silicon was inserted inside the nanolayers of Co-LDHs producing nanofibers of Si/Co LDHs through the intercalation of cyanate anions as pillars for building nanolayered structures. Additionally, nanoparticles were observed by controlling the preparation conditions and the silicon percentage. Scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy and thermal analyses have been used to characterize the nanolayered structures of Si/Co LDHs. The electrochemical characterization was performed by cyclic voltammetry and galvanic charge–discharge technique in 2M KOH electrolyte solution using three-electrode cell system. The calculated specific capacitance results indicated that the change of morphology from nanoparticles or plates to nanofibers had a positive effect for improving the performance of specific capacitance of Si/Co LDHs. The specific capacitance enhanced to be 621.5 F g⁻¹ in the case of the nanofiber of Si/Co LDHs. Similarly, the excellent cyclic stability (84.5%) was observed for the nanofiber. These results were explained through the attribute of the nanofibrous morphology and synergistic effects between the electric double layer capacitive character of the silicon and the pseudo capacitance nature of the cobalt. The high capacitance of ternary Si/Co/cyanate LDHs nanocomposites was suggested to be used as active electrode materials for high-performance supercapacitors applications. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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9 pages, 1111 KiB

Open AccessArticle

Damage Accumulation Phenomena in Multilayer (TiAlCrSiY)N/(TiAlCr)N, Monolayer (TiAlCrSiY)N Coatings and Silicon upon Deformation by Cyclic Nanoindentation

by Anatoly I. Kovalev, Vladimir O. Vakhrushev, Ben D. Beake, Egor P. Konovalov, Dmitry L. Wainstein, Stanislav A. Dmitrievskii, German S. Fox-Rabinovich and Stephen Veldhuis

Nanomaterials 2022, 12(8), 1312; https://doi.org/10.3390/nano12081312 - 11 Apr 2022

Cited by 2 | Viewed by 1496

Abstract

The micromechanism of the low-cycle fatigue of mono- and multilayer PVD coatings on cutting tools was investigated. Multilayer nanolaminate (TiAlCrSiY)N/(TiAlCr)N and monolayer (TiAlCrSiY)N PVD coatings were deposited on the cemented carbide ball nose end mills. Low-cycle fatigue resistance was studied using the cyclic [...] Read more.

The micromechanism of the low-cycle fatigue of mono- and multilayer PVD coatings on cutting tools was investigated. Multilayer nanolaminate (TiAlCrSiY)N/(TiAlCr)N and monolayer (TiAlCrSiY)N PVD coatings were deposited on the cemented carbide ball nose end mills. Low-cycle fatigue resistance was studied using the cyclic nanoindentation technique. The obtained results were compared with the behaviour of the polycrystalline silicon reference sample. The fractal analysis of time-resolved curves for indenter penetration depth demonstrated regularities of damage accumulation in the coatings at the early stage of wear. The difference in low-cycle fatigue of the brittle silicon and nitride wear-resistant coatings is shown. It is demonstrated that when distinguished from the single layer (TiAlCrSiY)N coating, the nucleation and growth of microcracks in the multilayer (TiAlCrSiY)N/(TiAlCr)N coating is accompanied by acts of microplastic deformation providing a higher fracture toughness of the multilayer nanolaminate (TiAlCrSiY)N/(TiAlCr)N. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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16 pages, 4185 KiB

Open AccessArticle

3D-Printable Oxygen- and Drug-Carrying Nanocomposite Hydrogels for Enhanced Cell Viability

by Ravi Kumar and Nermin Seda Kehr

Nanomaterials 2022, 12(8), 1304; https://doi.org/10.3390/nano12081304 - 11 Apr 2022

Cited by 8 | Viewed by 1944

Abstract

Nanocomposite (NC) hydrogels have been widely studied due to their tunable biochemical/ physical properties for tissue engineering and biomedical applications. Nanoparticles (NPs) that can carry bioactive hydrophilic/hydrophobic molecules and provide sustained release within hydrogels are an ideal all-in-one-platform for local drug delivery applications. [...] Read more.

Nanocomposite (NC) hydrogels have been widely studied due to their tunable biochemical/ physical properties for tissue engineering and biomedical applications. Nanoparticles (NPs) that can carry bioactive hydrophilic/hydrophobic molecules and provide sustained release within hydrogels are an ideal all-in-one-platform for local drug delivery applications. Dual delivery of different bioactive molecules is desired to achieve synergetic therapeutic effect in biomedical applications. For example, the co-administration of drug molecules and oxygen (O₂) is an ideal choice to improve cell viability, while reducing the harmful effects of hypoxia. Therefore, we prepared drug-loaded O₂-carrying periodic mesoporous organosilica (PMO-PFC) NPs and their 3D-printable hydrogel precursors based on gelatin methacryloyl (GelMa) to fabricate 3D-scaffolds to improve cell-viability under both normoxia (21% O₂) and hypoxia (1% O₂) conditions. We used rutin as the hydrophobic drug molecule to demonstrate that our O₂-carrying PMO-PFC NPs can improve hydrophobic drug loading and their sustained delivery over 7 days, while supporting sustained O₂-delivery for 14 days under hypoxia conditions. Furthermore, the fibroblast cells were interacted with NC hydrogel scaffolds to test their impact on cell-viability under both normoxia and hypoxia conditions. The improved rheological properties suggest the prepared NC hydrogels can be further tested or used as an injectable hydrogel. The improved mechanical properties and 3D printability of NC hydrogels indicate their potential use as artificial tissue constructs. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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11 pages, 3254 KiB

Open AccessArticle

Fabrication and Photocatalytic Properties of Zinc Tin Oxide Nanowires Decorated with Silver Nanoparticles

by Jia-Chi Su, Tsung-Lin Hsieh, Shu-Meng Yang, Shao-Chun Chao and Kuo-Chang Lu

Nanomaterials 2022, 12(7), 1201; https://doi.org/10.3390/nano12071201 - 03 Apr 2022

Cited by 4 | Viewed by 2103

Abstract

With the continuous advancement of high-tech industries, how to properly handle pollutants has become urgent. Photocatalysis is a solution that may effectively degrade pollutants into harmless molecules. In this study, we synthesized single crystalline Zn₂SnO₄ (ZTO) nanowires through chemical vapor [...] Read more.

With the continuous advancement of high-tech industries, how to properly handle pollutants has become urgent. Photocatalysis is a solution that may effectively degrade pollutants into harmless molecules. In this study, we synthesized single crystalline Zn₂SnO₄ (ZTO) nanowires through chemical vapor deposition and selective etching. The chemical bath redox method was used to modify the ZTO nanowires with Ag nanoparticles to explore the photocatalytic properties of the nanoheterostructures. The combination of the materials here is rare. Optical measurements by photoluminescence (PL) and UV–Vis show that the PL spectrum of ZTO nanowires was mainly in the visible light region and attributed to oxygen vacancies. The luminescence intensity of the nanowires was significantly reduced after modification, demonstrating that the heterojunction could effectively reduce the electron-hole pair recombination. The reduction increased with the increase in Ag decoration. The conversion from the UV–Vis absorption spectrum to the Tauc Plot shows that the band gap of the nanowire was 4.05 eV. With 10 ppm methylene blue (MB) as the degradation solution, ZTO nanowires exhibit excellent photodegradation efficiency. Reusability and stability in photodegradation of the nanowires were demonstrated. Photocatalytic efficiency increases with the number of Ag nanoparticles. The main reaction mechanism was confirmed by photocatalytic inhibitors. This study enriches our understanding of ZTO-based nanostructures and facilitates their applications in water splitting, sewage treatment and air purification. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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8 pages, 2947 KiB

Open AccessArticle

Optically Controlled Terahertz Dynamic Beam Splitter with Adjustable Split Ratio

by Shan Yin, Dehui Zeng, Yuting Chen, Wei Huang, Cheng Zhang, Wentao Zhang and Yiwen E

Nanomaterials 2022, 12(7), 1169; https://doi.org/10.3390/nano12071169 - 31 Mar 2022

Cited by 9 | Viewed by 2125

Abstract

The beam splitter is an important functional device due to its ability to steer the propagation of electromagnetic waves. The split-ratio-variable splitter is of significance for optical, terahertz and microwave systems. Here, we are the first (to our knowledge) to propose an optically [...] Read more.

The beam splitter is an important functional device due to its ability to steer the propagation of electromagnetic waves. The split-ratio-variable splitter is of significance for optical, terahertz and microwave systems. Here, we are the first (to our knowledge) to propose an optically controlled dynamic beam splitter with adjustable split ratio in the terahertz region. Based on the metasurface containing two sets of reversed phase-gradient supercells, we split the terahertz wave into two symmetrical beams. Associated with the reconfigurable pump laser pattern programmed with the spatial light modulator, dynamic modulation of the split ratio varying from 1:1 to 15:1 is achieved. Meanwhile, the beam splitter works at a split angle of 36° for each beam. Additionally, we obtain an exponential relationship between the split ratio and the illumination proportion, which can be used as theoretical guidance for beam splitting with an arbitrary split ratio. Our novel beam splitter shows an outstanding level of performance in terms of the adjustable split ratio and stable split angles and can be used as an advanced method to develop active functional devices applied to terahertz systems and communications. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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14 pages, 8363 KiB

Open AccessArticle

Silkworm Protein-Derived Nitrogen-Doped Carbon-Coated Li[Ni_0.8Co_0.15Al_0.05]O₂ for Lithium-Ion Batteries

by Gyu Sang Sim, Nitheesha Shaji, P. Santhoshkumar, Jae Woo Park, Chang Won Ho, Murugan Nanthagopal, Hong Ki Kim and Chang Woo Lee

Nanomaterials 2022, 12(7), 1166; https://doi.org/10.3390/nano12071166 - 31 Mar 2022

Cited by 5 | Viewed by 1690

Abstract

Li[Ni_0.8Co_0.15Al_0.05]O₂ (NCA) is a cathode material for lithium-ion batteries and has high power density and capacity. However, this material has disadvantages such as structural instability and short lifespan. To address these issues, herein, we explore the [...] Read more.

Li[Ni_0.8Co_0.15Al_0.05]O₂ (NCA) is a cathode material for lithium-ion batteries and has high power density and capacity. However, this material has disadvantages such as structural instability and short lifespan. To address these issues, herein, we explore the impact of N-doped carbon wrapping on NCA. Sericin, an easily obtained carbon- and nitrogen-rich component of silk cocoons, is utilized as the precursor material. The electrochemical performance evaluation of N-doped carbon-coated NCA shows that the capacity retention of 0.3 NC@NCA at 1C current density is 69.83% after 200 cycles, which is about 19% higher than the 50.65% capacity retention of bare NCA. The results reveal that the sericin-resultant N-doped carbon surface wrapping improves the cycling stability of NC@NCA. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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14 pages, 3851 KiB

Open AccessArticle

Synchronous Defect and Interface Engineering of NiMoO₄ Nanowire Arrays for High-Performance Supercapacitors

by Pengcheng Wang, Xinying Ding, Rongjie Zhe, Ting Zhu, Chen Qing, Yingkai Liu and Hong-En Wang

Nanomaterials 2022, 12(7), 1094; https://doi.org/10.3390/nano12071094 - 26 Mar 2022

Cited by 24 | Viewed by 2239

Abstract

Developing high-performance electrode materials is in high demand for the development of supercapacitors. Herein, defect and interface engineering has been simultaneously realized in NiMoO₄ nanowire arrays (NWAs) using a simple sucrose coating followed by an annealing process. The resultant hierarchical oxygen-deficient NiMoO [...] Read more.

Developing high-performance electrode materials is in high demand for the development of supercapacitors. Herein, defect and interface engineering has been simultaneously realized in NiMoO₄ nanowire arrays (NWAs) using a simple sucrose coating followed by an annealing process. The resultant hierarchical oxygen-deficient NiMoO₄@C NWAs (denoted as “NiMoO_4−x@C”) are grown directly on conductive ferronickel foam substrates. This composite affords direct electrical contact with the substrates and directional electron transport, as well as short ionic diffusion pathways. Furthermore, the coating of the amorphous carbon shell and the introduction of oxygen vacancies effectively enhance the electrical conductivity of NiMoO₄. In addition, the coated carbon layer improves the structural stability of the NiMoO₄ in the whole charging and discharging process, significantly enhancing the cycling stability of the electrode. Consequently, the NiMoO_4−x@C electrode delivers a high areal capacitance of 2.24 F cm⁻² (1720 F g⁻¹) at a current density of 1 mA cm⁻² and superior cycling stability of 84.5% retention after 6000 cycles at 20 mA cm⁻². Furthermore, an asymmetric super-capacitor device (ASC) has been constructed with NiMoO_4−x@C as the positive electrode and activated carbon (AC) as the negative electrode. The as-assembled ASC device shows excellent electrochemical performance with a high energy density of 51.6 W h kg⁻¹ at a power density of 203.95 W kg⁻¹. Moreover, the NiMoO₄//AC ASC device manifests remarkable cyclability with 84.5% of capacitance retention over 6000 cycles. The results demonstrate that the NiMoO_4−x@C composite is a promising material for electrochemical energy storage. This work can give new insights on the design and development of novel functional electrode materials via defect and interface engineering through simple yet effective chemical routes. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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14 pages, 4602 KiB

Open AccessArticle

Deformation Mechanism of Depositing Amorphous Cu-Ta Alloy Film via Nanoindentation Test

by Weibing Li, Xiao Wang, Xiaobin Feng, Yao Du, Xu Zhang, Yong Xie, Xiaoming Chen, Yang Lu and Weidong Wang

Nanomaterials 2022, 12(6), 1022; https://doi.org/10.3390/nano12061022 - 21 Mar 2022

Cited by 4 | Viewed by 2196

Abstract

As a representative of immiscible alloy systems, the Cu-Ta system was the research topic because of its potential application in industry, military and defense fields. In this study, an amorphous Cu-Ta alloy film was manufactured through magnetron sputter deposition, which was characterized by [...] Read more.

As a representative of immiscible alloy systems, the Cu-Ta system was the research topic because of its potential application in industry, military and defense fields. In this study, an amorphous Cu-Ta alloy film was manufactured through magnetron sputter deposition, which was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Mechanical properties of Cu-Ta film were detected by the nanoindentation method, which show that the elastic modulus of Cu3.5Ta96.5 is 156.7 GPa, and the hardness is 14.4 GPa. The nanoindentation process was also simulated by molecular dynamic simulation to indicate the deformation mechanism during the load-unload stage. The simulation results show that the structure <0,2,8,4> and <0,2,8,5> Voronoi cells decreased by 0.1% at 50 Ps and then remained at this value during the nanoindentation process. In addition, the number of dislocations vary rapidly with the depth between indenter and surface. Based on the experimental and simulation results, the Voronoi structural changes and dislocation motions are the key reasons for the crystallization of amorphous alloys when loads are applied. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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10 pages, 1593 KiB

Open AccessArticle

Reduced Electron Temperature in Silicon Multi-Quantum-Dot Single-Electron Tunneling Devices

by Youngmin Lee, So Hyun Lee, Hyo Seok Son and Sejoon Lee

Nanomaterials 2022, 12(4), 603; https://doi.org/10.3390/nano12040603 - 11 Feb 2022

Cited by 3 | Viewed by 1879

Abstract

The high-performance room-temperature-operating Si single-electron transistors (SETs) were devised in the form of the multiple quantum-dot (MQD) multiple tunnel junction (MTJ) system. The key device architecture of the Si MQD MTJ system was self-formed along the volumetrically undulated [110] Si nanowire that was [...] Read more.

The high-performance room-temperature-operating Si single-electron transistors (SETs) were devised in the form of the multiple quantum-dot (MQD) multiple tunnel junction (MTJ) system. The key device architecture of the Si MQD MTJ system was self-formed along the volumetrically undulated [110] Si nanowire that was fabricated by isotropic wet etching and subsequent oxidation of the e-beam-lithographically patterned [110] Si nanowire. The strong subband modulation in the volumetrically undulated [110] Si nanowire could create both the large quantum level spacings and the high tunnel barriers in the Si MQD MTJ system. Such a device scheme can not only decrease the cotunneling effect, but also reduce the effective electron temperature. These eventually led to the energetic stability for both the Coulomb blockade and the negative differential conductance characteristics at room temperature. The results suggest that the present device scheme (i.e., [110] Si MQD MTJ) holds great promise for the room-temperature demonstration of the high-performance Si SETs. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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16 pages, 7168 KiB

Open AccessArticle

Process Optimization for Manufacturing Functional Nanosurfaces by Roll-to-Roll Nanoimprint Lithography

by Usama Tahir, Jin Il Kim, Shama Javeed, Amin Khaliq, Jun-Hyun Kim, Doo-In Kim and Myung Yung Jeong

Nanomaterials 2022, 12(3), 480; https://doi.org/10.3390/nano12030480 - 29 Jan 2022

Cited by 9 | Viewed by 2543

Abstract

Roll-to-roll nanoimprint lithography (RTR-NIL) is a low-cost and continuous fabrication process for large-area functional films. However, the partial ultraviolet (UV) resin filling obstructs the ongoing production process. This study incorporates UV resin filling process into the nanopillars and nanopores by using RTR-NIL. A [...] Read more.

Roll-to-roll nanoimprint lithography (RTR-NIL) is a low-cost and continuous fabrication process for large-area functional films. However, the partial ultraviolet (UV) resin filling obstructs the ongoing production process. This study incorporates UV resin filling process into the nanopillars and nanopores by using RTR-NIL. A multiphase numerical model with a sliding mesh method is proposed in this study to show the actual phenomena of imprint mold rotation and feeding of UV resin on the polyethylene terephthalate (PET) substrate. The implementation of UV resin filling under environmental conditions was performed by utilizing the open-channel (OC) boundary conditions. The numerical model was solved by using the explicit volume of fluid (VOF) scheme to compute the filling on each node of the computational domain. The effects of different processing parameters were investigated through the proposed numerical model such as imprinting speed (IS), contact angles (CAs), viscosity, initial thickness of the PET, and supporting roll diameter. A good agreement was found between numerical simulations and experimental results. The proposed numerical model gives better insights of the filling process for the mass production of functional surfaces with nanopillars and nanopores patterns for different applications on an industrial scale. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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12 pages, 2706 KiB

Open AccessArticle

Ti₃Si_0.75Al_0.25C₂ Nanosheets as Promising Anode Material for Li-Ion Batteries

by Jianguang Xu, Qiang Wang, Boman Li, Wei Yao and Meng He

Nanomaterials 2021, 11(12), 3449; https://doi.org/10.3390/nano11123449 - 20 Dec 2021

Cited by 7 | Viewed by 2713

Abstract

Herein we report that novel two-dimensional (2D) Ti₃Si_0.75Al_0.25C₂ (TSAC) nanosheets, obtained by sonically exfoliating their bulk counterpart in alcohol, performs promising electrochemical activities in a reversible lithiation and delithiation procedure. The as-exfoliated 2D TSAC nanosheets show [...] Read more.

Herein we report that novel two-dimensional (2D) Ti₃Si_0.75Al_0.25C₂ (TSAC) nanosheets, obtained by sonically exfoliating their bulk counterpart in alcohol, performs promising electrochemical activities in a reversible lithiation and delithiation procedure. The as-exfoliated 2D TSAC nanosheets show significantly enhanced lithium-ion uptake capability in comparison with their bulk counterpart, with a high capacity of ≈350 mAh g⁻¹ at 200 mA g⁻¹, high cycling stability and excellent rate performance (150 mAh g⁻¹ after 200 cycles at 8000 mA g⁻¹). The enhanced electrochemical performance of TSAC nanosheets is mainly a result of their fast Li-ion transport, large surface area and small charge transfer resistance. The discovery in this work highlights the uniqueness of a family of 2D layered MAX materials, such as Ti₃GeC₂, Ti₃SnC₂ and Ti₂SC, which will likely be the promising choices as anode materials for lithium-ion batteries (LIBs). Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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14 pages, 6518 KiB

Open AccessArticle

Degradation of Acid Red 1 Catalyzed by Peroxidase Activity of Iron Oxide Nanoparticles and Detected by SERS

by Edna Vázquez-Vélez, Horacio Martínez and Fermín Castillo

Nanomaterials 2021, 11(11), 3044; https://doi.org/10.3390/nano11113044 - 12 Nov 2021

Cited by 3 | Viewed by 1657

Abstract

Magnetic iron oxide nanoparticles (MIONPs) were synthesized using tannic acid and characterized by Raman, FTIR, UV, and DRX spectroscopy. In a heterogeneous Fenton-like reaction, the catalytic peroxidase-like activity of MIONPs in the degradation of Acid Red 1 (AR 1) dye was investigated. TEM/STEM [...] Read more.

Magnetic iron oxide nanoparticles (MIONPs) were synthesized using tannic acid and characterized by Raman, FTIR, UV, and DRX spectroscopy. In a heterogeneous Fenton-like reaction, the catalytic peroxidase-like activity of MIONPs in the degradation of Acid Red 1 (AR 1) dye was investigated. TEM/STEM was used to determine the quasi-spherical morphology and particle size (3.2 nm) of the synthesized MIONPs. The XRD powder patterns were indexed according to the reverse spinel structure of magnetite, and SEM-EDS analysis confirmed their chemical composition. At pH = 3.5, the decomposition of H₂O₂ in hydroxyl radicals by MIONPs results in high AR 1 degradation (99%). This behavior was attributed to the size and surface properties of the MIONPs. Finally, the Surface Enhanced Raman Spectroscopy (SERS) technique detected intermediary compounds in the degradation process. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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11 pages, 2609 KiB

Open AccessArticle

Effect of Point Defects on Electronic Structure of Monolayer GeS

by Hyeong-Kyu Choi, Janghwan Cha, Chang-Gyu Choi, Junghwan Kim and Suklyun Hong

Nanomaterials 2021, 11(11), 2960; https://doi.org/10.3390/nano11112960 - 04 Nov 2021

Cited by 3 | Viewed by 1961

Abstract

Using density functional theory calculations, atomic and electronic structure of defects in monolayer GeS were investigated by focusing on the effects of vacancies and substitutional atoms. We chose group IV or chalcogen elements as substitutional ones, which substitute for Ge or S in [...] Read more.

Using density functional theory calculations, atomic and electronic structure of defects in monolayer GeS were investigated by focusing on the effects of vacancies and substitutional atoms. We chose group IV or chalcogen elements as substitutional ones, which substitute for Ge or S in GeS. It was found that the bandgap of GeS with substitutional atoms is close to that of pristine GeS, while the bandgap of GeS with Ge or S vacancies was smaller than that of pristine GeS. In terms of formation energy, monolayer GeS with Ge vacancies is more stable than that with S vacancies, and notably GeS with Ge substituted with Sn is most favorable within the range of chemical potential considered. Defects affect the piezoelectric properties depending on vacancies or substitutional atoms. Especially, GeS with substitutional atoms has almost the same piezoelectric stress coefficients

e_{i j}

as pristine GeS while having lower piezoelectric strain coefficients

d_{i j}

but still much higher than other 2D materials. It is therefore concluded that Sn can effectively heal Ge vacancy in GeS, keeping high piezoelectric strain coefficients. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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12 pages, 3844 KiB

Open AccessArticle

Vertically Aligned Binder-Free TiO₂ Nanotube Arrays Doped with Fe, S and Fe-S for Li-ion Batteries

by Suriyakumar Dasarathan, Mukarram Ali, Tai-Jong Jung, Junghwan Sung, Yoon-Cheol Ha, Jun-Woo Park and Doohun Kim

Nanomaterials 2021, 11(11), 2924; https://doi.org/10.3390/nano11112924 - 31 Oct 2021

Cited by 5 | Viewed by 2928

Abstract

Vertically aligned Fe, S, and Fe-S doped anatase TiO₂ nanotube arrays are prepared by an electrochemical anodization process using an organic electrolyte in which lactic acid is added as an additive. In the electrolyte, highly ordered TiO₂ nanotube layers with greater [...] Read more.

Vertically aligned Fe, S, and Fe-S doped anatase TiO₂ nanotube arrays are prepared by an electrochemical anodization process using an organic electrolyte in which lactic acid is added as an additive. In the electrolyte, highly ordered TiO₂ nanotube layers with greater thickness of 12 μm, inner diameter of approx. 90 nm and outer diameter of approx. 170 nm are successfully obtained. Doping of Fe, S, and Fe-S via simple wet impregnation method substituted Ti and O sites with Fe and S, which leads to enhance the rate performance at high discharge C-rates. Discharge capacities of TiO₂ tubes increased from 0.13 mAh cm⁻²(bare) to 0.28 mAh cm⁻² for Fe-S doped TiO₂ at 0.5 C after 100 cycles with exceptional capacity retention of 85 % after 100 cycles. Owing to the enhancement of thermodynamic and kinetic properties by doping of Fe-S, Li-diffusion increased resulting in remarkable discharge capacities of 0.27 mAh cm⁻² and 0.16 mAh cm⁻² at 10 C, and 30 C, respectively. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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15 pages, 2937 KiB

Open AccessFeature PaperArticle

Extended Graphite Supported Flower-like MnO₂ as Bifunctional Materials for Supercapacitors and Glucose Sensing

by Han-Wei Chang, Chung-Li Dong, Yan-Hua Chen, Yuan-Zhang Xu, Tzu-Chi Huang, Song-Chi Chen, Feng-Jiin Liu, Yin-Hung Lai and Yu-Chen Tsai

Nanomaterials 2021, 11(11), 2881; https://doi.org/10.3390/nano11112881 - 28 Oct 2021

Cited by 4 | Viewed by 1719

Abstract

A simple, efficient, and cost-effective extended graphite as a supporting platform further supported the MnO₂ growth for the construction of hierarchical flower-like MnO₂/extended graphite. MnO₂/extended graphite exhibited an increase in sp² carbon bonds in comparison with that [...] Read more.

A simple, efficient, and cost-effective extended graphite as a supporting platform further supported the MnO₂ growth for the construction of hierarchical flower-like MnO₂/extended graphite. MnO₂/extended graphite exhibited an increase in sp² carbon bonds in comparison with that of extended graphite. It can be expected to display better electrical conductivity and further promote electron/ion transport kinetics for boosting the electrochemical performance in supercapacitors and glucose sensing. In supercapacitors, MnO₂/extended graphite delivered an areal capacitance value of 20.4 mF cm⁻² at 0.25 mA cm⁻² current densities and great cycling stability (capacitance retention of 83% after 1000 cycles). In glucose sensing, MnO₂/extended graphite exhibited a good linear relationship in glucose concentration up to about 5 mM, sensitivity of 43 μA mM⁻¹cm⁻², and the limit of detection of 0.081 mM. It is further concluded that MnO₂/extended graphite could be a good candidate for the future design of synergistic multifunctional materials in electrochemical techniques. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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6 pages, 7914 KiB

Open AccessArticle

Enhanced Hole Injection Characteristics of a Top Emission Organic Light-Emitting Diode with Pure Aluminum Anode

by Chan Young Park and Byoungdeog Choi

Nanomaterials 2021, 11(11), 2869; https://doi.org/10.3390/nano11112869 - 27 Oct 2021

Cited by 7 | Viewed by 2438

Abstract

A top emitting organic light-emitting diode (OLED) device with pure aluminum (Al) anode for high-resolution microdisplays was proposed and fabricated. The low work function of the Al anode, even with a native oxide formed on the Al anode surface, increases the energy barrier [...] Read more.

A top emitting organic light-emitting diode (OLED) device with pure aluminum (Al) anode for high-resolution microdisplays was proposed and fabricated. The low work function of the Al anode, even with a native oxide formed on the Al anode surface, increases the energy barrier of the interface between the anode and hole injection layer, and has poor hole-injection properties, which causes the low efficiency of the device. To enhance the hole-injection characteristics of the Al anode, we applied hexaazatriphenylene hexacarbonitrile (HATCN) as the hole-injection layer material. The proposed OLED device with a pure Al anode and native oxide on the anode surface improved efficiency by up to 35 cd/A at 1000 nit, which is 78% of the level of normal OLEDs with indium tin oxide (ITO) anode. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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16 pages, 5503 KiB

Open AccessEditor’s ChoiceArticle

Mesoporous Zn/MgO Hexagonal Nano-Plates as a Catalyst for Camelina Oil Biodiesel Synthesis

by Lai-Fan Man, Tsz-Lung Kwong, Wing-Tak Wong and Ka-Fu Yung

Nanomaterials 2021, 11(10), 2690; https://doi.org/10.3390/nano11102690 - 13 Oct 2021

Cited by 5 | Viewed by 1898

Abstract

A novel mesoporous Zn/MgO hexagonal-nano-plate catalyst was synthesized by a simple template-free hydrothermal method and applied in the base-catalyzed transesterification of Camelina oil for biodiesel synthesis. The Zn/MgO catalyst calcinated at 873 K exhibited the highest catalytic activity with a yield of 88.7%. [...] Read more.

A novel mesoporous Zn/MgO hexagonal-nano-plate catalyst was synthesized by a simple template-free hydrothermal method and applied in the base-catalyzed transesterification of Camelina oil for biodiesel synthesis. The Zn/MgO catalyst calcinated at 873 K exhibited the highest catalytic activity with a yield of 88.7%. This catalytic reaction was performed using 3% w/w of the catalyst with a methanol-to-oil molar ratio of 24:1 at 393 K in 8 h. The excellent catalytic performance is possibly attributed to its favorable textural features with relatively high surface area (69.1 m² g⁻¹) and appropriate size of the mesopores (10.4 nm). In addition, the as-synthesized catalyst demonstrated a greater basic sites density than single mesoporous MgO, which might have been promoted by the addition of Zn, leading to a synergetic interaction that enhanced its catalytic activity. This catalytic system demonstrated high stability for five catalytic runs and catalytic activity with over 84% yield. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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13 pages, 4140 KiB

Open AccessArticle

The Deactivation Mechanism of the Mo-Ce/Zr-PILC Catalyst Induced by Pb for the Selective Catalytic Reduction of NO with NH₃

by Chenxi Li, Jin Cheng, Qing Ye, Fanwei Meng, Xinpeng Wang and Hongxing Dai

Nanomaterials 2021, 11(10), 2641; https://doi.org/10.3390/nano11102641 - 07 Oct 2021

Cited by 2 | Viewed by 1652

Abstract

As a heavy metal, Pb is one component in coal-fired flue gas and is widely considered to have a strong negative effect on catalyst activity in the selective catalytic reduction of NO_x by NH₃ (NH₃-SCR). In this paper, we [...] Read more.

As a heavy metal, Pb is one component in coal-fired flue gas and is widely considered to have a strong negative effect on catalyst activity in the selective catalytic reduction of NO_x by NH₃ (NH₃-SCR). In this paper, we investigated the deactivation mechanism of the Mo-Ce/Zr-PILC catalyst induced by Pb in detail. We found that NO conversion over the 3Mo4Ce/Zr-PILC catalyst decreased greatly after the addition of Pb. The more severe deactivation induced by Pb was attributed to low surface area, lower amounts of chemisorbed oxygen species and surface Ce³⁺, and lower redox ability and surface acidity (especially a low number of Brønsted acid sites). Furthermore, the addition of Pb inhibited the formation of highly active intermediate nitrate species generated on the surface of the catalyst, hence decreasing the NH₃-SCR activity. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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14 pages, 6763 KiB

Open AccessArticle

Simple Self-Assembly Strategy of Nanospheres on 3D Substrate and Its Application for Enhanced Textured Silicon Solar Cell

by Dan Su, Lei Lv, Yi Yang, Huan-Li Zhou, Sami Iqbal and Tong Zhang

Nanomaterials 2021, 11(10), 2581; https://doi.org/10.3390/nano11102581 - 30 Sep 2021

Cited by 5 | Viewed by 1827

Abstract

Nanomaterials and nanostructures provide new opportunities to achieve high-performance optical and optoelectronic devices. Three-dimensional (3D) surfaces commonly exist in those devices (such as light-trapping structures or intrinsic grains), and here, we propose requests for nanoscale control over nanostructures on 3D substrates. In this [...] Read more.

Nanomaterials and nanostructures provide new opportunities to achieve high-performance optical and optoelectronic devices. Three-dimensional (3D) surfaces commonly exist in those devices (such as light-trapping structures or intrinsic grains), and here, we propose requests for nanoscale control over nanostructures on 3D substrates. In this paper, a simple self-assembly strategy of nanospheres for 3D substrates is demonstrated, featuring controllable density (from sparse to close-packed) and controllable layer (from a monolayer to multi-layers). Taking the assembly of wavelength-scale SiO₂ nanospheres as an example, it has been found that textured 3D substrate promotes close-packed SiO₂ spheres compared to the planar substrate. Distribution density and layers of SiO₂ coating can be well controlled by tuning the assembly time and repeating the assembly process. With such a versatile strategy, the enhancement effects of SiO₂ coating on textured silicon solar cells were systematically examined by varying assembly conditions. It was found that the close-packed SiO₂ monolayer yielded a maximum relative efficiency enhancement of 9.35%. Combining simulation and macro/micro optical measurements, we attributed the enhancement to the nanosphere-induced concentration and anti-reflection of incident light. The proposed self-assembly strategy provides a facile and cost-effective approach for engineering nanomaterials at 3D interfaces. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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12 pages, 2036 KiB

Open AccessArticle

Extensive Broadband Near-Infrared Emissions from Ge_xSi_1−x Alloys on Micro-Hole Patterned Si(001) Substrates

by Kun Peng, Ningning Zhang, Jiarui Zhang, Peizong Chen, Jia Yan, Changlin Zheng, Zuimin Jiang and Zhenyang Zhong

Nanomaterials 2021, 11(10), 2545; https://doi.org/10.3390/nano11102545 - 28 Sep 2021

Cited by 1 | Viewed by 2165

Abstract

Broadband near-infrared (NIR) luminescent materials have been continuously pursued as promising candidates for optoelectronic devices crucial for wide applications in night vision, environment monitoring, biological imaging, etc. Here, graded Ge_xSi_1−x (x = 0.1–0.3) alloys are grown on micro-hole patterned Si(001) [...] Read more.

Broadband near-infrared (NIR) luminescent materials have been continuously pursued as promising candidates for optoelectronic devices crucial for wide applications in night vision, environment monitoring, biological imaging, etc. Here, graded Ge_xSi_1−x (x = 0.1–0.3) alloys are grown on micro-hole patterned Si(001) substrates. Barn-like islands and branch-like nanostructures appear at regions in-between micro-holes and the sidewalls of micro-holes, respectively. The former is driven by the efficient strain relation. The latter is induced by the dislocations originating from defects at sidewalls after etching. An extensive broadband photoluminescence (PL) spectrum is observed in the NIR wavelength range of 1200–2200 nm. Moreover, the integrated intensity of the PL can be enhanced by over six times in comparison with that from the reference sample on a flat substrate. Such an extensively broad and strong PL spectrum is attributed to the coupling between the emissions of GeSi alloys and the guided resonant modes in ordered micro-holes and the strain-enhanced decomposition of alloys during growth on the micro-hole patterned substrate. These results demonstrate that the graded Ge_xSi_1−x alloys on micro-hole pattered Si substrates may have great potential for the development of innovative broadband NIR optoelectronic devices, particularly to realize entire systems on a Si chip. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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11 pages, 5984 KiB

Open AccessArticle

Nitrogen-Containing Gas Sensing Properties of 2-D Ti₂N and Its Derivative Nanosheets: Electronic Structures Insight

by Hongni Zhang, Wenzheng Du, Jianjun Zhang, Rajeev Ahuja and Zhao Qian

Nanomaterials 2021, 11(9), 2459; https://doi.org/10.3390/nano11092459 - 21 Sep 2021

Cited by 5 | Viewed by 2470

Abstract

In this work, the potentials of two-dimensional Ti₂N and its derivative nanosheets Ti₂NT₂(T=O, F, OH) for some harmful nitrogen-containing gas (NCG) adsorption and sensing applications have been unveiled based on the quantum-mechanical Density Functional Theory calculations. It [...] Read more.

In this work, the potentials of two-dimensional Ti₂N and its derivative nanosheets Ti₂NT₂(T=O, F, OH) for some harmful nitrogen-containing gas (NCG) adsorption and sensing applications have been unveiled based on the quantum-mechanical Density Functional Theory calculations. It is found that the interactions between pure Ti₂N and NCGs (including NO, NO₂, and NH₃ in this study) are very strong, in which NO and NO₂ can even be dissociated, and this would poison the substrate of Ti₂N monolayer and affect the stability of the sensing material. For the monolayer of Ti₂NT₂(T=O, F, OH) that is terminated by functional groups on surface, the adsorption energies of NCGs are greatly reduced, and a large amount of charges are transferred to the functional group, which is beneficial to the reversibility of the sensing material. The significant changes in work function imply the good sensitivity of the above mentioned materials. In addition, the fast response time further consolidates the prospect of two-dimensional Ti₂NT₂ as efficient NCGs’ sensing materials. This theoretical study would supply physical insight into the NCGs’ sensing mechanism of Ti₂N based nanosheets and help experimentalists to design better 2-D materials for gas adsorption or sensing applications. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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13 pages, 3430 KiB

Open AccessCommunication

Photocatalytic Degradation of Tobacco Tar Using CsPbBr3 Quantum Dots Modified Bi2WO6 Composite Photocatalyst

by Runda Huang, Menglong Zhang, Zhaoqiang Zheng, Kunqiang Wang, Xiao Liu, Qizan Chen and Dongxiang Luo

Nanomaterials 2021, 11(9), 2422; https://doi.org/10.3390/nano11092422 - 17 Sep 2021

Cited by 9 | Viewed by 2676

Abstract

Polycyclic aromatic hydrocarbons (PAHs) in tobacco tar are regarded as a significant threat to human health. PAHs are formed due to the incomplete combustion of organics in tobacco and cigarette paper. Herein, for the first time, we extended the application of CsPbBr₃ [...] Read more.

Polycyclic aromatic hydrocarbons (PAHs) in tobacco tar are regarded as a significant threat to human health. PAHs are formed due to the incomplete combustion of organics in tobacco and cigarette paper. Herein, for the first time, we extended the application of CsPbBr₃ quantum dots (CsPbBr₃) to the photocatalytic degradation of tobacco tar, which was collected from used cigarette filters. To optimize the photoactivity, CsPbBr₃ was coupled with Bi₂WO₆ for the construction of a type-II photocatalyst. The photocatalytic performance of the CsPbBr₃/Bi₂WO₆ composite was evaluated by the degradation rate of PAHs from tobacco tar under simulated solar irradiation. The results revealed that CsPbBr₃/Bi₂WO₆ possesses a large specific surface area, outstanding absorption ability, good light absorption and rapid charge separation. As a result, in addition to good stability, the composite photocatalyst performed remarkably well in degrading PAHs (over 96% were removed in 50 mins of irradiation by AM 1.5 G). This study sheds light on promising novel applications of halide perovskite. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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13 pages, 3004 KiB

Open AccessArticle

Evaluating a Human Ear-Inspired Sound Pressure Amplification Structure with Fabry–Perot Acoustic Sensor Using Graphene Diaphragm

by Cheng Li, Xi Xiao, Yang Liu and Xuefeng Song

Nanomaterials 2021, 11(9), 2284; https://doi.org/10.3390/nano11092284 - 02 Sep 2021

Cited by 7 | Viewed by 2724

Abstract

In order to enhance the sensitivity of a Fabry–Perot (F-P) acoustic sensor without the need of fabricating complicated structures of the acoustic-sensitive diaphragm, a mini-type external sound pressure amplification structure (SPAS) with double 10 μm thickness E-shaped diaphragms of different sizes interconnected with [...] Read more.

In order to enhance the sensitivity of a Fabry–Perot (F-P) acoustic sensor without the need of fabricating complicated structures of the acoustic-sensitive diaphragm, a mini-type external sound pressure amplification structure (SPAS) with double 10 μm thickness E-shaped diaphragms of different sizes interconnected with a 5 mm length tapered circular rod was developed based on the acoustic sensitive mechanism of the ossicular chain in the human middle ear. The influence of thickness and Young’s modulus of the two diaphragms with the diameters of 15 mm and 3 mm, respectively, on the amplification ratio and frequency response were investigated via COMSOL acoustic field simulation, thereby confirming the dominated effect. Then, three kinds of dual-diaphragm schemes relating to steel and thermoplastic polyurethanes (TPU) materials were introduced to fabricate the corresponding SPASs. The acoustic test showed that the first scheme achieved a high resonant response frequency with lower acoustic amplification due to strong equivalent stiffness; in contrast, the second scheme offered a high acoustic amplification but reduced frequency range. As a result of sensitivity enhancement, adapted with the steel/TPU diaphragm structure, an optical fiber Fabry–Perot sensor using a multilayer graphene diaphragm with a diameter of 125 μm demonstrated a remarkable sensitivity of 565.3 mV/Pa @1.2 kHz due to the amplification ratio of up to ~29.9 in the range of 0.2–2.3 kHz, which can be further improved by miniaturizing structure dimension, along with the use of microstructure packaging technology. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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8 pages, 1941 KiB

Open AccessArticle

In-Sn-Zn Oxide Nanocomposite Films with Enhanced Electrical Properties Deposited by High-Power Impulse Magnetron Sputtering

by Hui Sun, Zhi-Yue Li, Sheng-Chi Chen, Ming-Han Liao, Jian-Hong Gong, Zhamatuofu Bai and Wan-Xia Wang

Nanomaterials 2021, 11(8), 2016; https://doi.org/10.3390/nano11082016 - 06 Aug 2021

Cited by 5 | Viewed by 1801

Abstract

In-Sn-Zn oxide (ITZO) nanocomposite films have been investigated extensively as a potential material in thin-film transistors due to their good electrical properties. In this work, ITZO thin films were deposited on glass substrates by high-power impulse magnetron sputtering (HiPIMS) at room temperature. The [...] Read more.

In-Sn-Zn oxide (ITZO) nanocomposite films have been investigated extensively as a potential material in thin-film transistors due to their good electrical properties. In this work, ITZO thin films were deposited on glass substrates by high-power impulse magnetron sputtering (HiPIMS) at room temperature. The influence of the duty cycle (pulse off-time) on the microstructures and electrical performance of the films was investigated. The results showed that ITZO thin films prepared by HiPIMS were dense and smooth compared to thin films prepared by direct-current magnetron sputtering (DCMS). With the pulse off-time increasing from 0 μs (DCMS) to 2000 μs, the films’ crystallinity enhanced. When the pulse off-time was longer than 1000 μs, In₂O₃ structure could be detected in the films. The films’ electrical resistivity reduced as the pulse off-time extended. Most notably, the optimal resistivity of as low as 4.07 × 10⁻³ Ω·cm could be achieved when the pulse off-time was 2000 μs. Its corresponding carrier mobility and carrier concentration were 12.88 cm²V⁻¹s⁻¹ and 1.25 × 10²⁰ cm⁻³, respectively. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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10 pages, 4170 KiB

Open AccessArticle

Multi-Angular Colorimetric Responses of Uni- and Omni-Directional Femtosecond Laser-Induced Periodic Surface Structures on Metals

by Taek-Yong Hwang, Yong-dae Kim, Jongweon Cho, Hai-Joong Lee, Hyo-Soo Lee and Byounghwak Lee

Nanomaterials 2021, 11(8), 2010; https://doi.org/10.3390/nano11082010 - 05 Aug 2021

Cited by 2 | Viewed by 1887

Abstract

We investigated the colorimetric behaviors of metal surfaces with unidirectional low-spatial-frequency laser-induced periodic surface structures (UD-LSFLs) and omnidirectional LSFLs (OD-LSFLs) fabricated using femtosecond laser pulse irradiation. With the CIE standard illuminant D65, incident at −45°, we show that UD-LSFLs on metals transform polished [...] Read more.

We investigated the colorimetric behaviors of metal surfaces with unidirectional low-spatial-frequency laser-induced periodic surface structures (UD-LSFLs) and omnidirectional LSFLs (OD-LSFLs) fabricated using femtosecond laser pulse irradiation. With the CIE standard illuminant D65, incident at −45°, we show that UD-LSFLs on metals transform polished metals to gonio-apparent materials with a unique behavior of colorimetric responses, depending on both the detection and rotation angles, whereas OD-LSFLs have nearly uniform gonio-apparent colors at each detection angle, regardless of their rotation. These colorimetric behaviors can be observed not only at the angles of diffraction but also near the angle of reflection, and we find that the power redistribution due to Rayleigh anomalies also plays an important role in the colorimetric responses of UD- and OD-LSFLs, in addition to diffraction. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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15 pages, 5738 KiB

Open AccessArticle

Effect of Water and Glycerol in Deoxygenation of Coconut Oil over Bimetallic NiCo/SAPO-11 Nanocatalyst under N₂ Atmosphere

by Rungnapa Kaewmeesri, Jeeranan Nonkumwong, Thongthai Witoon, Navadol Laosiripojana and Kajornsak Faungnawakij

Nanomaterials 2020, 10(12), 2548; https://doi.org/10.3390/nano10122548 - 18 Dec 2020

Cited by 3 | Viewed by 2181

Abstract

The catalytic deoxygenation of coconut oil was performed in a continuous-flow reactor over bimetallic NiCo/silicoaluminophosphate-11 (SAPO-11) nanocatalysts for hydrocarbon fuel production. The conversion and product distribution were investigated over NiCo/SAPO-11 with different applied co-reactants, i.e., water (H₂O) or glycerol solution, performed [...] Read more.

The catalytic deoxygenation of coconut oil was performed in a continuous-flow reactor over bimetallic NiCo/silicoaluminophosphate-11 (SAPO-11) nanocatalysts for hydrocarbon fuel production. The conversion and product distribution were investigated over NiCo/SAPO-11 with different applied co-reactants, i.e., water (H₂O) or glycerol solution, performed under nitrogen (N₂) atmosphere. The hydrogen-containing co-reactants were proposed here as in-situ hydrogen sources for the deoxygenation, while the reaction tests under hydrogen (H₂) atmosphere were also applied as a reference set of experiments. The results showed that applying co-reactants to the reaction enhanced the oil conversion as the following order: N₂ (no co-reactant) < N₂ (H₂O) < N₂ (aqueous glycerol) < H₂ (reference). The main products formed under the existence of H₂O or glycerol solution were free fatty acids (FFAs) and their corresponding C_n−1 alkanes. The addition of H₂O aids the triglyceride breakdown into FFAs, whereas the glycerol acts as hydrogen donor which is favourable to initiate hydrogenolysis of triglycerides, causing higher amount of FFAs than the former case. Consequently, those FFAs can be deoxygenated via decarbonylation/decarboxylation to their corresponding C_n−1 alkanes, showing the promising capability of the NiCo/SAPO-11 to produce hydrocarbon fuels even in the absence of external H₂ source. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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13 pages, 6122 KiB

Open AccessArticle

Low-Temperature Synthesis of Monolithic Titanium Carbide/Carbon Composite Aerogel

by Tingting Niu, Bin Zhou, Zehui Zhang, Xiujie Ji, Jianming Yang, Yuhan Xie, Hongqiang Wang and Ai Du

Nanomaterials 2020, 10(12), 2527; https://doi.org/10.3390/nano10122527 - 16 Dec 2020

Cited by 4 | Viewed by 2344

Abstract

Resorcinol-formaldehyde/titanium dioxide composite (RF/TiO₂) gel was prepared simultaneously by acid catalysis and then dried to aerogel with supercritical fluid CO₂. The carbon/titanium dioxide aerogel was obtained by carbonization and then converted to nanoporous titanium carbide/carbon composite aerogel via 800 [...] Read more.

Resorcinol-formaldehyde/titanium dioxide composite (RF/TiO₂) gel was prepared simultaneously by acid catalysis and then dried to aerogel with supercritical fluid CO₂. The carbon/titanium dioxide aerogel was obtained by carbonization and then converted to nanoporous titanium carbide/carbon composite aerogel via 800 °C magnesiothermic catalysis. Meanwhile, the evolution of the samples in different stages was characterized by X-ray diffraction (XRD), an energy-dispersive X-ray (EDX) spectrometer, a scanning electron microscope (SEM), a transmission electron microscope (TEM) and specific surface area analysis (BET). The results showed that the final product was nanoporous TiC/C composite aerogel with a low apparent density of 339.5 mg/cm³ and a high specific surface area of 459.5 m²/g. Comparing to C aerogel, it could also be considered as one type of highly potential material with efficient photothermal conversion. The idea of converting oxide–carbon composite into titanium carbide via the confining template and low-temperature magnesiothermic catalysis may provide new sight to the synthesis of novel nanoscale carbide materials. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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9 pages, 1632 KiB

Open AccessArticle

Improved Pulse-Controlled Conductance Adjustment in Trilayer Resistors by Suppressing Current Overshoot

by Hojeong Ryu and Sungjun Kim

Nanomaterials 2020, 10(12), 2462; https://doi.org/10.3390/nano10122462 - 09 Dec 2020

Cited by 4 | Viewed by 1642

Abstract

In this work, we demonstrate the enhanced synaptic behaviors in trilayer dielectrics (HfO₂/Si₃N₄/SiO₂) on highly doped n-type silicon substrate. First, the three dielectric layers were subjected to material and chemical analyses and thoroughly investigated via [...] Read more.

In this work, we demonstrate the enhanced synaptic behaviors in trilayer dielectrics (HfO₂/Si₃N₄/SiO₂) on highly doped n-type silicon substrate. First, the three dielectric layers were subjected to material and chemical analyses and thoroughly investigated via transmission electron microscopy and X-ray photoelectron spectroscopy. The resistive switching and synaptic behaviors were improved by inserting a Si₃N₄ layer between the HfO₂ and SiO₂ layers. The electric field within SiO₂ was mitigated, thus reducing the current overshoot in the trilayer device. The reset current was considerably reduced in the trilayer device compared to the bilayer device without a Si₃N₄ layer. Moreover, the nonlinear characteristics in the low-resistance state are helpful for implementing high-density memory. The higher array size in the trilayer device was verified by cross-point array simulation. Finally, the multiple conductance adjustment was demonstrated in the trilayer device by controlling the gradual set and reset switching behavior. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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11 pages, 3287 KiB

Open AccessArticle

Creation of Curved Nanostructures Using Soft-Materials-Derived Lithography

by Hyun-Ik Jang, Hae-Su Yoon, Tae-Ik Lee, Sangmin Lee, Taek-Soo Kim, Jaesool Shim and Jae Hong Park

Nanomaterials 2020, 10(12), 2414; https://doi.org/10.3390/nano10122414 - 03 Dec 2020

Cited by 2 | Viewed by 2097

Abstract

In this study, curved nanostructures, which are difficult to obtain, were created on an Si substrate through the bonding, swelling, and breaking processes of the polymer and silicone substrate. This method can be utilized to obtain convex nanostructures over large areas. The method [...] Read more.

In this study, curved nanostructures, which are difficult to obtain, were created on an Si substrate through the bonding, swelling, and breaking processes of the polymer and silicone substrate. This method can be utilized to obtain convex nanostructures over large areas. The method is simpler than typical semiconductor processing with photolithography or compared to wet- or vacuum-based dry etching processes. The polymer bonding, swelling (or no swelling), and breaking processes that are performed in this process were theoretically analyzed through a numerical analysis of permeability and modeling. Through this process, we designed a convex nanostructure that can be produced experimentally in an accurate manner. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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15 pages, 3990 KiB

Open AccessArticle

Influence of Oxygen Flow Rate on Channel Width Dependent Electrical Properties of Indium Gallium Zinc Oxide Thin-Film Transistors

by Gwomei Wu and Anup K. Sahoo

Nanomaterials 2020, 10(12), 2357; https://doi.org/10.3390/nano10122357 - 27 Nov 2020

Cited by 15 | Viewed by 3706

Abstract

The effects of various oxygen flows on indium gallium zinc oxide (IGZO) based thin-film transistors (TFTs) with different channel width sizes have been investigated. The IGZO nano-films exhibited amorphous phase while the bandgap energy and sheet resistance increased with increasing oxygen flow rate. [...] Read more.

The effects of various oxygen flows on indium gallium zinc oxide (IGZO) based thin-film transistors (TFTs) with different channel width sizes have been investigated. The IGZO nano-films exhibited amorphous phase while the bandgap energy and sheet resistance increased with increasing oxygen flow rate. The electrical characteristics were evaluated with different sizes in channel width using fixed channel length. The distributions in terms of threshold voltage and current on–off level along the different channel width sizes have been discussed thoroughly. The minimum distribution of threshold voltage was observed at an oxygen flow rate of 1 sccm. The TFT electrical properties have been achieved, using an oxygen flow rate of 1 sccm with 500 µm channel width, the threshold voltage, ratio of on-current to off-current, sub-threshold swing voltage and field effect mobility to be 0.54 V, 10⁶, 0.15 V/decade and 12.3 cm²/V·s, respectively. On the other hand, a larger channel width of 2000 µm could further improve the ratio of on-current to off-current and sub-threshold swing voltage to 10⁷ and 0.11 V/decade. The optimized combination of oxygen flow and channel width showed improved electrical characteristics for TFT applications. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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23 pages, 7116 KiB

Open AccessArticle

Manganese Ferrite Nanoparticles (MnFe₂O₄): Size Dependence for Hyperthermia and Negative/Positive Contrast Enhancement in MRI

by Khairul Islam, Manjurul Haque, Arup Kumar, Amitra Hoq, Fahmeed Hyder and Sheikh Manjura Hoque

Nanomaterials 2020, 10(11), 2297; https://doi.org/10.3390/nano10112297 - 20 Nov 2020

Cited by 80 | Viewed by 6821

Abstract

We synthesized manganese ferrite (MnFe₂O₄) nanoparticles of different sizes by varying pH during chemical co-precipitation procedure and modified their surfaces with polysaccharide chitosan (CS) to investigate characteristics of hyperthermia and magnetic resonance imaging (MRI). Structural features were analyzed by [...] Read more.

We synthesized manganese ferrite (MnFe₂O₄) nanoparticles of different sizes by varying pH during chemical co-precipitation procedure and modified their surfaces with polysaccharide chitosan (CS) to investigate characteristics of hyperthermia and magnetic resonance imaging (MRI). Structural features were analyzed by X-ray diffraction (XRD), high-resolution transmission electron microscopy (TEM), selected area diffraction (SAED) patterns, and Mössbauer spectroscopy to confirm the formation of superparamagnetic MnFe₂O₄ nanoparticles with a size range of 5–15 nm for pH of 9–12. The hydrodynamic sizes of nanoparticles were less than 250 nm with a polydispersity index of 0.3, whereas the zeta potentials were higher than 30 mV to ensure electrostatic repulsion for stable colloidal suspension. MRI properties at 7T demonstrated that transverse relaxation (T₂) doubled as the size of CS-coated MnFe₂O₄ nanoparticles tripled in vitro. However, longitudinal relaxation (T₁) was strongest for the smallest CS-coated MnFe₂O₄ nanoparticles, as revealed by in vivo positive contrast MRI angiography. Cytotoxicity assay on HeLa cells showed CS-coated MnFe₂O₄ nanoparticles is viable regardless of ambient pH, whereas hyperthermia studies revealed that both the maximum temperature and specific loss power obtained by alternating magnetic field exposure depended on nanoparticle size and concentration. Overall, these results reveal the exciting potential of CS-coated MnFe₂O₄ nanoparticles in MRI and hyperthermia studies for biomedical research. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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12 pages, 3688 KiB

Open AccessArticle

Adhesion of Escherichia Coli to Nanostructured Surfaces and the Role of Type 1 Fimbriae

by Pawel Kallas, Håvard J Haugen, Nikolaj Gadegaard, John Stormonth-Darling, Mats Hulander, Martin Andersson and Håkon Valen

Nanomaterials 2020, 10(11), 2247; https://doi.org/10.3390/nano10112247 - 12 Nov 2020

Cited by 11 | Viewed by 3732

Abstract

Bacterial fimbriae are an important virulence factor mediating adhesion to both biotic and abiotic surfaces and facilitating biofilm formation. The expression of type 1 fimbriae of Escherichia coli is a key virulence factor for urinary tract infections and catheter-associated urinary tract infections, which [...] Read more.

Bacterial fimbriae are an important virulence factor mediating adhesion to both biotic and abiotic surfaces and facilitating biofilm formation. The expression of type 1 fimbriae of Escherichia coli is a key virulence factor for urinary tract infections and catheter-associated urinary tract infections, which represent the most common nosocomial infections. New strategies to reduce adhesion of bacteria to surfaces is therefore warranted. The aim of the present study was to investigate how surfaces with different nanotopography-influenced fimbriae-mediated adhesion. Surfaces with three different nanopattern surface coverages made in polycarbonate were fabricated by injection molding from electron beam lithography nanopatterned templates. The surfaces were constructed with features of approximately 40 nm width and 25 nm height with 100 nm, 250 nm, and 500 nm interspace distance, respectively. The role of fimbriae type 1-mediated adhesion was investigated using the E. coli wild type BW25113 and ΔfimA (with a knockout of major pilus protein FimA) and ΔfimH (with a knockout of minor protein FimH) mutants. For the surfaces with nanotopography, all strains adhered least to areas with the largest interpillar distance (500 nm). For the E. coli wild type, no difference in adhesion between surfaces without pillars and the largest interpillar distance was observed. For the deletion mutants, increased adhesion was observed for surfaces without pillars compared to surfaces with the largest interpillar distance. The presence of a fully functional type 1 fimbria decreased the bacterial adhesion to the nanopatterned surfaces in comparison to the mutants. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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15 pages, 9023 KiB

Open AccessArticle

Preparation and Photocatalytic Performance for Degradation of Rhodamine B of AgPt/Bi₄Ti₃O₁₂ Composites

by Gaoqian Yuan, Gen Zhang, Kezhuo Li, Faliang Li, Yunbo Cao, Jiangfeng He, Zhong Huang, Quanli Jia, Shaowei Zhang and Haijun Zhang

Nanomaterials 2020, 10(11), 2206; https://doi.org/10.3390/nano10112206 - 05 Nov 2020

Cited by 12 | Viewed by 2330

Abstract

Loading a noble metal on Bi₄Ti₃O₁₂ could enable the formation of the Schottky barrier at the interface between the former and the latter, which causes electrons to be trapped and inhibits the recombination of photoelectrons and photoholes. In [...] Read more.

Loading a noble metal on Bi₄Ti₃O₁₂ could enable the formation of the Schottky barrier at the interface between the former and the latter, which causes electrons to be trapped and inhibits the recombination of photoelectrons and photoholes. In this paper, AgPt/Bi₄Ti₃O₁₂ composite photocatalysts were prepared using the photoreduction method, and the effects of the type and content of noble metal on the photocatalytic performance of the catalysts were investigated. The photocatalytic degradation of rhodamine B (RhB) showed that the loading of AgPt bimetallic nanoparticles significantly improved the catalytic performance of Bi₄Ti₃O₁₂. When 0.10 wt% noble metal was loaded, the degradation rate for RhB of Ag_0.7Pt_0.3/Bi₄Ti₃O₁₂ was 0.027 min⁻¹, which was respectively about 2, 1.7 and 3.7 times as that of Ag/Bi₄Ti₃O₁₂, Pt/Bi₃Ti₄O₁₂ and Bi₄Ti₃O_12. The reasons may be attributed as follows: (i) the utilization of visible light was enhanced due to the surface plasmon resonance effect of Ag and Pt in the visible region; (ii) Ag nanoparticles mainly acted as electron acceptors to restrain the recombination of photogenerated electron-hole pairs under visible light irradiation; and (iii) Pt nanoparticles acted as electron cocatalysts to further suppress the recombination of photogenerated electron-hole pairs. The photocatalytic performance of Ag_0.7Pt_0.3/Bi₄Ti₃O₁₂ was superior to that of Ag/Bi₄Ti₃O₁₂ and Pt/Bi₃Ti₄O₁₂ owing to the synergistic effect between Ag and Pt nanoparticles. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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13 pages, 3993 KiB

Open AccessArticle

Hexagonal and Monoclinic Phases of La₂O₂CO₃ Nanoparticles and Their Phase-Related CO₂ Behavior

by Hongyan Yu, Kaiming Jiang, Sung Gu Kang, Yong Men and Eun Woo Shin

Nanomaterials 2020, 10(10), 2061; https://doi.org/10.3390/nano10102061 - 19 Oct 2020

Cited by 9 | Viewed by 2929

Abstract

In this study, we prepared hexagonal and monoclinic phases of La₂O₂CO₃ nanoparticles by different wet preparation methods and investigated their phase-related CO₂ behavior through field-emission scanning microscopy, high-resolution transmission electron microscopy, Fourier transform infrared, thermogravimetric analysis, CO [...] Read more.

In this study, we prepared hexagonal and monoclinic phases of La₂O₂CO₃ nanoparticles by different wet preparation methods and investigated their phase-related CO₂ behavior through field-emission scanning microscopy, high-resolution transmission electron microscopy, Fourier transform infrared, thermogravimetric analysis, CO₂-temperature programmed desorption, and linear sweeping voltammetry of CO₂ electrochemical reduction. The monoclinic La₂O₂CO₃ phase was synthesized by a conventional precipitation method via La(OH)CO₃ when the precipitation time was longer than 12 h. In contrast, the hydrothermal method produced only the hexagonal La₂O₂CO₃ phase, irrespective of the hydrothermal reaction time. The La(OH)₃ phase was determined to be the initial phase in both preparation methods. During the precipitation, the La(OH)₃ phase was transformed into La(OH)CO₃ owing to the continuous supply of CO₂ from air whereas the hydrothermal method of a closed system crystallized only the La(OH)₃ phase. Based on the CO₂-temperature programmed desorption and thermogravimetric analysis, the hexagonal La₂O₂CO₃ nanoparticles (HL-12h) showed a higher surface CO₂ adsorption and thermal stability than those of the monoclinic La₂O₂CO₃ (PL-12h). The crystalline structures of both La₂O₂CO₃ phases predicted by the density functional theory calculation explained the difference in the CO₂ behavior on each phase. Consequently, HL-12h showed a higher current density and a more positive onset potential than PL-12h in CO₂ electrochemical reduction. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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18 pages, 4957 KiB

Open AccessArticle

Hydrogen Peroxide Detection by Super-Porous Hybrid CuO/Pt NP Platform: Improved Sensitivity and Selectivity

by Rakesh Kulkarni, Sundar Kunwar, Rutuja Mandavkar, Jae-Hun Jeong and Jihoon Lee

Nanomaterials 2020, 10(10), 2034; https://doi.org/10.3390/nano10102034 - 15 Oct 2020

Cited by 7 | Viewed by 2539

Abstract

A super-porous hybrid platform can offer significantly increased number of reaction sites for the analytes and thus can offer advantages in the biosensor applications. In this work, a significantly improved sensitivity and selectivity of hydrogen peroxide (H₂O₂) detection is [...] Read more.

A super-porous hybrid platform can offer significantly increased number of reaction sites for the analytes and thus can offer advantages in the biosensor applications. In this work, a significantly improved sensitivity and selectivity of hydrogen peroxide (H₂O₂) detection is demonstrated by a super-porous hybrid CuO/Pt nanoparticle (NP) platform on Si substrate as the first demonstration. The super-porous hybrid platform is fabricated by a physiochemical approach combining the physical vapor deposition of Pt NPs and electrochemical deposition of super-porous CuO structures by adopting a dynamic hydrogen bubble technique. Under an optimized condition, the hybrid CuO/Pt biosensor demonstrates a very high sensitivity of 2205 µA/mM·cm² and a low limit of detection (LOD) of 140 nM with a wide detection range of H₂O₂. This is meaningfully improved performance as compared to the previously reported CuO-based H₂O₂ sensors as well as to the other metal oxide-based H₂O₂ sensors. The hybrid CuO/Pt platform exhibits an excellent selectivity against other interfering molecules such as glucose, fructose, dopamine, sodium chloride and ascorbic acid. Due to the synergetic effect of highly porous CuO structures and underlying Pt NPs, the CuO/Pt architecture offers extremely abundant active sites for the H₂O₂ reduction and electron transfer pathways. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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11 pages, 6286 KiB

Open AccessArticle

Soft X-ray Absorption Spectroscopic Investigation of Li(Ni_0.8Co_0.1Mn_0.1)O₂ Cathode Materials

by Jitendra Pal Singh, Jae Yeon Park, Keun Hwa Chae, Docheon Ahn and Sangsul Lee

Nanomaterials 2020, 10(4), 759; https://doi.org/10.3390/nano10040759 - 15 Apr 2020

Cited by 8 | Viewed by 4590

Abstract

Herein, we report the soft X-ray absorption spectroscopic investigation for Li(Ni_0.8Co_0.1Mn_0.1)O₂ cathode material during charging and discharging. These measurements were carried out at the Mn L-, Co L-, and Ni L-edges during various [...] Read more.

Herein, we report the soft X-ray absorption spectroscopic investigation for Li(Ni_0.8Co_0.1Mn_0.1)O₂ cathode material during charging and discharging. These measurements were carried out at the Mn L-, Co L-, and Ni L-edges during various stages of charging and discharging. Both the Mn and Co L-edge spectroscopic measurements reflect the invariance in the oxidation states of Mn and Co ions. The Ni L-edge measurements show the modification of the oxidation state of Ni ions during the charging and discharging process. These studies show that e_g states are affected dominantly in the case of Ni ions during the charging and discharging process. The O K-edge measurements reflect modulation of metal–oxygen hybridization as envisaged from the area-ratio variation of spectral features corresponding to t_2g and e_g states. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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9 pages, 6376 KiB

Open AccessCommunication

Design of Heat-Conductive hBN–PMMA Composites by Electrostatic Nano-Assembly

by Atsushi Yokoi, Wai Kian Tan, Taichi Kuroda, Go Kawamura, Atsunori Matsuda and Hiroyuki Muto

Nanomaterials 2020, 10(1), 134; https://doi.org/10.3390/nano10010134 - 12 Jan 2020

Cited by 13 | Viewed by 3522

Abstract

Micro/nanoscale design of composite materials enables alteration of their properties for advanced functional materials. One of the biggest challenges in material design is the controlled decoration of composite materials with the desired functional additives. This study reports on and demonstrates the homogeneous decoration [...] Read more.

Micro/nanoscale design of composite materials enables alteration of their properties for advanced functional materials. One of the biggest challenges in material design is the controlled decoration of composite materials with the desired functional additives. This study reports on and demonstrates the homogeneous decoration of hexagonal boron nitride (hBN) on poly(methylmethacrylate) (PMMA) and vice versa. The formation of the composite materials was conducted via a low environmental load and a low-energy-consuming, electrostatic nano-assembly method which also enabled the efficient usage of nano-sized additives. The hBN/PMMA and PMMA/hBN composites were fabricated in various size combinations that exhibited percolated and layer-oriented structures, respectively. The thermal conductivity behaviors of hBN/PMMA and PMMA/hBN composites that exhibited good microstructure were compared. The results showed that microstructural design of the composites enabled the modification of their heat-conducting property. This novel work demonstrated the feasibility of fabricating heat-conductive PMMA matrix composites with controlled decoration of hBN sheets, which may provide a platform for further development of heat-conductive polymeric materials. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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Review

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24 pages, 1212 KiB

Open AccessReview

Applications of Nano Hydroxyapatite as Adsorbents: A Review

by Iresha Lakmali Balasooriya, Jia Chen, Sriyani Menike Korale Gedara, Yingchao Han and Merita Nirmali Wickramaratne

Nanomaterials 2022, 12(14), 2324; https://doi.org/10.3390/nano12142324 - 06 Jul 2022

Cited by 25 | Viewed by 3491

Abstract

Nano hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂, HAp) has aroused widespread attention as a green and environmentally friendly adsorbent due to its outstanding ability in removing heavy metal ions, radio nuclides, organic pollutants and fluoride ions for wastewater treatment. [...] Read more.

Nano hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂, HAp) has aroused widespread attention as a green and environmentally friendly adsorbent due to its outstanding ability in removing heavy metal ions, radio nuclides, organic pollutants and fluoride ions for wastewater treatment. The hexagonal crystal structure of HAp supports the adsorption mechanisms including ionic exchange reaction, surface complexation, the co-precipitation of new partially soluble phases and physical adsorption such as electrostatic interaction and hydrogen bonding. However, nano HAp has some drawbacks such as agglomeration and a significant pressure drop during filtration when used in powder form. Therefore, instead of using nano HAp alone, researchers have worked on modificationsand composites of nano HAp to overcome these issues and enhance the adsorption capacity. The modification of cationic doping and organic molecule grafting for nano HAp can promote the immobilization of ions and then increase adsorption capacity. Developing nano HAp composite with biopolymers such as gelatin, chitosan and chitin has proven to obtain a synergetic effect for improving the adsorption capacity of composites, in which nano HAp fixed and dispersed in polymers can playmuch more of a role for adsorption. This review summarizes the adsorption properties and adsorbent applications of nano HAp as well as the methods to enhance the adsorption capacity of nano HAp. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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21 pages, 4047 KiB

Open AccessReview

Single-Element 2D Materials beyond Graphene: Methods of Epitaxial Synthesis

by Kirill A. Lozovoy, Ihor I. Izhnin, Andrey P. Kokhanenko, Vladimir V. Dirko, Vladimir P. Vinarskiy, Alexander V. Voitsekhovskii, Olena I. Fitsych and Nataliya Yu. Akimenko

Nanomaterials 2022, 12(13), 2221; https://doi.org/10.3390/nano12132221 - 28 Jun 2022

Cited by 16 | Viewed by 2921

Abstract

Today, two-dimensional materials are one of the key research topics for scientists around the world. Interest in 2D materials is not surprising because, thanks to their remarkable mechanical, thermal, electrical, magnetic, and optical properties, they promise to revolutionize electronics. The unique properties of [...] Read more.

Today, two-dimensional materials are one of the key research topics for scientists around the world. Interest in 2D materials is not surprising because, thanks to their remarkable mechanical, thermal, electrical, magnetic, and optical properties, they promise to revolutionize electronics. The unique properties of graphene-like 2D materials give them the potential to create completely new types of devices for functional electronics, nanophotonics, and quantum technologies. This paper considers epitaxially grown two-dimensional allotropic modifications of single elements: graphene (C) and its analogs (transgraphenes) borophene (B), aluminene (Al), gallenene (Ga), indiene (In), thallene (Tl), silicene (Si), germanene (Ge), stanene (Sn), plumbene (Pb), phosphorene (P), arsenene (As), antimonene (Sb), bismuthene (Bi), selenene (Se), and tellurene (Te). The emphasis is put on their structural parameters and technological modes in the method of molecular beam epitaxy, which ensure the production of high-quality defect-free single-element two-dimensional structures of a large area for promising device applications. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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18 pages, 5684 KiB

Open AccessReview

Recycling and Reutilizing Polymer Waste via Electrospun Micro/Nanofibers: A Review

by Xiuhong Li, Yujie Peng, Yichen Deng, Fangping Ye, Chupeng Zhang, Xinyu Hu, Yong Liu and Daode Zhang

Nanomaterials 2022, 12(10), 1663; https://doi.org/10.3390/nano12101663 - 13 May 2022

Cited by 9 | Viewed by 3466

Abstract

The accumulation of plastic waste resulting from the increasing demand for non-degradable plastics has led to a global environmental crisis. The severe environmental and economic drawbacks of inefficient, expensive, and impractical traditional waste disposal methods, such as landfills, incineration, plastic recycling, and energy [...] Read more.

The accumulation of plastic waste resulting from the increasing demand for non-degradable plastics has led to a global environmental crisis. The severe environmental and economic drawbacks of inefficient, expensive, and impractical traditional waste disposal methods, such as landfills, incineration, plastic recycling, and energy production, limit the expansion of their applications to solving the plastic waste problem. Finding novel ways to manage the large amount of disposed plastic waste is urgent. Until now, one of the most valuable strategies for the handling of plastic waste has been to reutilize the waste as raw material for the preparation of functional and high-value products. Electrospun micro/nanofibers have drawn much attention in recent years due to their advantages of small diameter, large specific area, and excellent physicochemical features. Thus, electrospinning recycled plastic waste into micro/nanofibers creates diverse opportunities to deal with the environmental issue caused by the growing accumulation of plastic waste. This paper presents a review of recycling and reutilizing polymer waste via electrospinning. Firstly, the advantages of the electrospinning approach to recycling plastic waste are summarized. Then, the studies of electrospun recycled plastic waste are concluded. Finally, the challenges and future perspectives of electrospun recycled plastic waste are provided. In conclusion, this paper aims to provide a comprehensive overview of electrospun recycled plastic waste for researchers to develop further studies. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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23 pages, 4311 KiB

Open AccessReview

A Review on Current Designation of Metallic Nanocomposite Hydrogel in Biomedical Applications

by Nur Syafiqah Farhanah Dzulkharnien and Rosiah Rohani

Nanomaterials 2022, 12(10), 1629; https://doi.org/10.3390/nano12101629 - 10 May 2022

Cited by 15 | Viewed by 2600

Abstract

In the past few decades, nanotechnology has been receiving significant attention globally and is being continuously developed in various innovations for diverse applications, such as tissue engineering, biotechnology, biomedicine, textile, and food technology. Nanotechnological materials reportedly lack cell-interactive properties and are easily degraded [...] Read more.

In the past few decades, nanotechnology has been receiving significant attention globally and is being continuously developed in various innovations for diverse applications, such as tissue engineering, biotechnology, biomedicine, textile, and food technology. Nanotechnological materials reportedly lack cell-interactive properties and are easily degraded into unfavourable products due to the presence of synthetic polymers in their structures. This is a major drawback of nanomaterials and is a cause of concern in the biomedicine field. Meanwhile, particulate systems, such as metallic nanoparticles (NPs), have captured the interest of the medical field due to their potential to inhibit the growth of microorganisms (bacteria, fungi, and viruses). Lately, researchers have shown a great interest in hydrogels in the biomedicine field due to their ability to retain and release drugs as well as to offer a moist environment. Hence, the development and innovation of hydrogel-incorporated metallic NPs from natural sources has become one of the alternative pathways for elevating the efficiency of therapeutic systems to make them highly effective and with fewer undesirable side effects. The objective of this review article is to provide insights into the latest fabricated metallic nanocomposite hydrogels and their current applications in the biomedicine field using nanotechnology and to discuss the limitations of this technology for future exploration. This article gives an overview of recent metallic nanocomposite hydrogels fabricated from bioresources, and it reviews their antimicrobial activities in facilitating the demands for their application in biomedicine. The work underlines the fabrication of various metallic nanocomposite hydrogels through the utilization of natural sources in the production of biomedical innovations, including wound healing treatment, drug delivery, scaffolds, etc. The potential of these nanocomposites in relation to their mechanical strength, antimicrobial activities, cytotoxicity, and optical properties has brought this technology into a new dimension in the biomedicine field. Finally, the limitations of metallic nanocomposite hydrogels in terms of their methods of synthesis, properties, and outlook for biomedical applications are further discussed. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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20 pages, 4059 KiB

Open AccessReview

Research Progress on Sound Absorption of Electrospun Fibrous Composite Materials

by Xiuhong Li, Yujie Peng, Youqi He, Chupeng Zhang, Daode Zhang and Yong Liu

Nanomaterials 2022, 12(7), 1123; https://doi.org/10.3390/nano12071123 - 29 Mar 2022

Cited by 13 | Viewed by 3661

Abstract

Noise is considered severe environmental pollutant that affects human health. Using sound absorption materials to reduce noise is a way to decrease the hazards of noise pollution. Micro/nanofibers have advantages in sound absorption due to their properties such as small diameter, large specific [...] Read more.

Noise is considered severe environmental pollutant that affects human health. Using sound absorption materials to reduce noise is a way to decrease the hazards of noise pollution. Micro/nanofibers have advantages in sound absorption due to their properties such as small diameter, large specific surface area, and high porosity. Electrospinning is a technology for producing micro/nanofibers, and this technology has attracted interest in the field of sound absorption. To broaden the applications of electrospun micro/nanofibers in acoustics, the present study of electrospun micro/nano fibrous materials for sound absorption is summarized. First, the factors affecting the micro/nanofibers’ sound absorption properties in the process of electrospinning are presented. Through changing the materials, process parameters, and duration of electrospinning, the properties, morphologies, and thicknesses of electrospun micro/nanofibers can be controlled. Hence, the sound absorption characteristics of electrospun micro/nanofibers will be affected. Second, the studies on porous sound absorbers, combined with electrospun micro/nanofibers, are introduced. Then, the studies of electrospun micro/nanofibers in resonant sound absorption are concluded. Finally, the shortcomings of electrospun micro/nano fibrous sound absorption materials are discussed, and the future research is forecasted. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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16 pages, 1765 KiB

Open AccessReview

Recent Advances in Synthesis, Medical Applications and Challenges for Gold-Coated Iron Oxide: Comprehensive Study

by Mohammed Ali Dheyab, Azlan Abdul Aziz, Mahmood S. Jameel and Pegah Moradi Khaniabadi

Nanomaterials 2021, 11(8), 2147; https://doi.org/10.3390/nano11082147 - 23 Aug 2021

Cited by 16 | Viewed by 2798

Abstract

Combining iron oxide nanoparticles (Fe₃O₄ NPs) and gold nanoparticles (Au NPs) in one nanostructure is a promising technique for various applications. Fe₃O₄ NPs have special supermagnetic attributes that allow them to be applied in different areas, and [...] Read more.

Combining iron oxide nanoparticles (Fe₃O₄ NPs) and gold nanoparticles (Au NPs) in one nanostructure is a promising technique for various applications. Fe₃O₄ NPs have special supermagnetic attributes that allow them to be applied in different areas, and Au NPs stand out in biomaterials due to their oxidation resistance, chemical stability, and unique optical properties. Recent studies have generally defined the physicochemical properties of nanostructures without concentrating on a particular formation strategy. This detailed review provides a summary of the latest research on the formation strategy and applications of Fe₃O₄@Au. The diverse methods of synthesis of Fe₃O₄@Au NPs with different basic organic and inorganic improvements are introduced. The role and applicability of Au coating on the surface of Fe₃O₄ NPs schemes were explored. The 40 most relevant publications were identified and reviewed. The versatility of combining Fe₃O₄@Au NPs as an option for medical application is proven in catalysis, hyperthermia, biomedical imaging, drug delivery and protein separation. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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20 pages, 3215 KiB

Open AccessReview

Metal-Based Nanomaterials: Work as Drugs and Carriers against Viral Infections

by Junlei Yang, Lihuan Yue, Zhu Yang, Yuqing Miao, Ruizhuo Ouyang and Yihong Hu

Nanomaterials 2021, 11(8), 2129; https://doi.org/10.3390/nano11082129 - 20 Aug 2021

Cited by 10 | Viewed by 2667

Abstract

Virus infection is one of the threats to the health of organisms, and finding suitable antiviral agents is one of the main tasks of current researchers. Metal ions participate in multiple key reaction stages of organisms and maintain the important homeostasis of organisms. [...] Read more.

Virus infection is one of the threats to the health of organisms, and finding suitable antiviral agents is one of the main tasks of current researchers. Metal ions participate in multiple key reaction stages of organisms and maintain the important homeostasis of organisms. The application of synthetic metal-based nanomaterials as an antiviral therapy is a promising new research direction. Based on the application of synthetic metal-based nanomaterials in antiviral therapy, we summarize the research progress of metal-based nanomaterials in recent years. This review analyzes the three inhibition pathways of metal nanomaterials as antiviral therapeutic materials against viral infections, including direct inactivation, inhibition of virus adsorption and entry, and intracellular virus suppression; it further classifies and summarizes them according to their inhibition mechanisms. In addition, the use of metal nanomaterials as antiviral drug carriers and vaccine adjuvants is summarized. The analysis clarifies the antiviral mechanism of metal nanomaterials and broadens the application in the field of antiviral therapy. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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26 pages, 3423 KiB

Open AccessReview

Metal Oxide Based Heterojunctions for Gas Sensors: A Review

by Shulin Yang, Gui Lei, Huoxi Xu, Zhigao Lan, Zhao Wang and Haoshuang Gu

Nanomaterials 2021, 11(4), 1026; https://doi.org/10.3390/nano11041026 - 17 Apr 2021

Cited by 80 | Viewed by 6043

Abstract

The construction of heterojunctions has been widely applied to improve the gas sensing performance of composites composed of nanostructured metal oxides. This review summarises the recent progress on assembly methods and gas sensing behaviours of sensors based on nanostructured metal oxide heterojunctions. Various [...] Read more.

The construction of heterojunctions has been widely applied to improve the gas sensing performance of composites composed of nanostructured metal oxides. This review summarises the recent progress on assembly methods and gas sensing behaviours of sensors based on nanostructured metal oxide heterojunctions. Various methods, including the hydrothermal method, electrospinning and chemical vapour deposition, have been successfully employed to establish metal oxide heterojunctions in the sensing materials. The sensors composed with the built nanostructured heterojunctions were found to show enhanced gas sensing performance with higher sensor responses and shorter response times to the targeted reducing or oxidising gases compare with those of the pure metal oxides. Moreover, the enhanced gas sensing mechanisms of the metal oxide-based heterojunctions to the reducing or oxidising gases are also discussed, with the main emphasis on the important role of the potential barrier on the accumulation layer. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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36 pages, 16038 KiB

Open AccessReview

Dendritic Polymers as Promising Additives for the Manufacturing of Hybrid Organoceramic Nanocomposites with Ameliorated Properties Suitable for an Extensive Diversity of Applications

by Marilina Douloudi, Eleni Nikoli, Theodora Katsika, Michalis Vardavoulias and Michael Arkas

Nanomaterials 2021, 11(1), 19; https://doi.org/10.3390/nano11010019 - 24 Dec 2020

Cited by 14 | Viewed by 2898

Abstract

As the field of nanoscience is rapidly evolving, interest in novel, upgraded nanomaterials with combinatory features is also inevitably increasing. Hybrid composites, offer simple, budget-conscious and environmental-friendly solutions that can cater multiple needs at the same time and be applicable in many nanotechnology-related [...] Read more.

As the field of nanoscience is rapidly evolving, interest in novel, upgraded nanomaterials with combinatory features is also inevitably increasing. Hybrid composites, offer simple, budget-conscious and environmental-friendly solutions that can cater multiple needs at the same time and be applicable in many nanotechnology-related and interdisciplinary studies. The physicochemical idiocrasies of dendritic polymers have inspired their implementation as sorbents, active ingredient carriers and templates for complex composites. Ceramics are distinguished for their mechanical superiority and absorption potential that render them ideal substrates for separation and catalysis technologies. The integration of dendritic compounds to these inorganic hosts can be achieved through chemical attachment of the organic moiety onto functionalized surfaces, impregnation and absorption inside the pores, conventional sol-gel reactions or via biomimetic mediation of dendritic matrices, inducing the formation of usually spherical hybrid nanoparticles. Alternatively, dendritic polymers can propagate from ceramic scaffolds. All these variants are covered in detail. Optimization techniques as well as established and prospected applications are also presented. Full article

(This article belongs to the Special Issue Nanotechnologies and Nanomaterials: Selected Papers from CCMR)

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