Nanomaterials

12 pages, 2292 KiB

Open AccessArticle

Spherical and Spindle-Like Abamectin-Loaded Nanoparticles by Flash Nanoprecipitation for Southern Root-Knot Nematode Control: Preparation and Characterization

by Zhinan Fu, Kai Chen, Li Li, Fang Zhao, Yan Wang, Mingwei Wang, Yue Shen, Haixin Cui, Dianhua Liu and Xuhong Guo

Nanomaterials 2018, 8(6), 449; https://doi.org/10.3390/nano8060449 - 20 Jun 2018

Cited by 26 | Viewed by 5009

Abstract

Southern root-knot nematode (Meloidogyne incognita) is a biotrophic parasite, causing enormous loss in global crop production annually. Abamectin (Abm) is a biological and high-efficiency pesticide against Meloidogyne incognita. In this study, a powerful method, flash nanoprecipitation (FNP), was adopted to [...] Read more.

Southern root-knot nematode (Meloidogyne incognita) is a biotrophic parasite, causing enormous loss in global crop production annually. Abamectin (Abm) is a biological and high-efficiency pesticide against Meloidogyne incognita. In this study, a powerful method, flash nanoprecipitation (FNP), was adopted to successfully produce Abm-loaded nanoparticle suspensions with high drug loading capacity (>40%) and encapsulation efficiency (>95%), where amphiphilic block copolymers (BCPs) poly(lactic-co-glycolic acid)-b-poly(ethylene glycol) (PLGA-b-PEG), poly(d,l-lactide)-b-poly(ethylene glycol) (PLA-b-PEG), or poly(caprolactone)-b-poly(ethylene glycol) (PCL-b-PEG) were used as the stabilizer to prevent the nanoparticles from aggregation. The effect of the drug-to-stabilizer feed ratio on the particle stability were investigated. Moreover, the effect of the BCP composition on the morphology of Abm-loaded nanoparticles for controlling Meloidogyne incognita were discussed. Notably, spindle-like nanoparticles were obtained with PCL-b-PEG as the stabilizer and found significantly more efficient (98.4% mortality at 1 ppm particle concentration) than spherical nanoparticles using PLGA-b-PEG or PLA-b-PEG as the stabilizer. This work provides a more rapid and powerful method to prepare stable Abm-loaded nanoparticles with tunable morphologies and improved effectiveness for controlling Meloidogyne incognita. Full article

(This article belongs to the Special Issue Self-Assembled Bio-Nanomaterials: Synthesis, Characterization, and Applications)

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8 pages, 711 KiB

Open AccessArticle

Measuring the Density of States of the Inner and Outer Wall of Double-Walled Carbon Nanotubes

by Benjamin A. Chambers, Cameron J. Shearer, LePing Yu, Christopher T. Gibson and Gunther G. Andersson

Nanomaterials 2018, 8(6), 448; https://doi.org/10.3390/nano8060448 - 19 Jun 2018

Cited by 4 | Viewed by 3974

Abstract

The combination of ultraviolet photoelectron spectroscopy and metastable helium induced electron spectroscopy is used to determine the density of states of the inner and outer coaxial carbon nanotubes. Ultraviolet photoelectron spectroscopy typically measures the density of states across the entire carbon nanotube, while [...] Read more.

The combination of ultraviolet photoelectron spectroscopy and metastable helium induced electron spectroscopy is used to determine the density of states of the inner and outer coaxial carbon nanotubes. Ultraviolet photoelectron spectroscopy typically measures the density of states across the entire carbon nanotube, while metastable helium induced electron spectroscopy measures the density of states of the outermost layer alone. The use of double-walled carbon nanotubes in electronic devices allows for the outer wall to be functionalised whilst the inner wall remains defect free and the density of states is kept intact for electron transport. Separating the information of the inner and outer walls enables development of double-walled carbon nanotubes to be independent, such that the charge transport of the inner wall is maintained and confirmed whilst the outer wall is modified for functional purposes. Full article

(This article belongs to the Special Issue Applications of Carbon Nanotubes)

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24 pages, 5532 KiB

Open AccessArticle

Numerical Comparison of Prediction Models for Aerosol Filtration Efficiency Applied on a Hollow-Fiber Membrane Pore Structure

by Pavel Bulejko

Nanomaterials 2018, 8(6), 447; https://doi.org/10.3390/nano8060447 - 19 Jun 2018

Cited by 21 | Viewed by 5746

Abstract

Hollow-fiber membranes (HFMs) have been widely applied to many liquid treatment applications such as wastewater treatment, membrane contactors/bioreactors and membrane distillation. Despite the fact that HFMs are widely used for gas separation from gas mixtures, their use for mechanical filtration of aerosols is [...] Read more.

Hollow-fiber membranes (HFMs) have been widely applied to many liquid treatment applications such as wastewater treatment, membrane contactors/bioreactors and membrane distillation. Despite the fact that HFMs are widely used for gas separation from gas mixtures, their use for mechanical filtration of aerosols is very scarce. In this work, we compared mathematical models developed for the prediction of air filtration efficiency by applying them on the structural parameters of polypropylene HFMs. These membranes are characteristic of pore diameters of about 90 nm and have high solidity, thus providing high potential for nanoparticle removal from air. A single fiber/collector and capillary pore approach was chosen to compare between models developed for fibrous filters and capillary-pore membranes (Nuclepore filters) based on three main mechanisms occurring in aerosol filtration (inertial impaction, interception and diffusion). The collection efficiency due to individual mechanisms differs significantly. The differences are caused by the parameters for which the individual models were developed, i.e., given values of governing dimensionless numbers (Reynolds, Stokes and Peclet number) and also given values of filter porosity and filter fiber diameter. Some models can be used to predict the efficiency of HFMs based on assumptions depending on the conditions and exact membrane parameters. Full article

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11 pages, 3117 KiB

Open AccessArticle

MIL-100(Al) Gels as an Excellent Platform Loaded with Doxorubicin Hydrochloride for pH-Triggered Drug Release and Anticancer Effect

by Yuge Feng, Chengliang Wang, Fei Ke, Jianye Zang and Junfa Zhu

Nanomaterials 2018, 8(6), 446; https://doi.org/10.3390/nano8060446 - 19 Jun 2018

Cited by 18 | Viewed by 5151

Abstract

Slow and controlled release systems for drugs have attracted increasing interest recently. A highly efficient metal-organic gel (MOGs) drug delivery carrier, i.e., MIL-100(Al) gel, has been fabricated by a facile, low cost, and environmentally friendly one-pot process. The unique structure of MIL-100(Al) gels [...] Read more.

Slow and controlled release systems for drugs have attracted increasing interest recently. A highly efficient metal-organic gel (MOGs) drug delivery carrier, i.e., MIL-100(Al) gel, has been fabricated by a facile, low cost, and environmentally friendly one-pot process. The unique structure of MIL-100(Al) gels has led to a high loading efficiency (620 mg/g) towards doxorubicin hydrochloride (DOX) as a kind of anticancer drug. DOX-loaded MOGs exhibited high stability under physiological conditions and sustained release capacity of DOX for up to three days (under acidic environments). They further showed sustained drug release behavior and excellent antitumor effects in in vitro experiments on HeLa cells, in contrast with the extremely low biotoxicity of MOGs. Our work provides a promising way for anticancer therapy by utilizing this MOGs-based drug delivery system as an efficient and safe vehicle. Full article

(This article belongs to the Special Issue Nanocolloids for Nanomedicine and Drug Delivery)

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13 pages, 4875 KiB

Open AccessArticle

Hydrophilic Chlorin e6-Poly(amidoamine) Dendrimer Nanoconjugates for Enhanced Photodynamic Therapy

by So-Ri Lee and Young-Jin Kim

Nanomaterials 2018, 8(6), 445; https://doi.org/10.3390/nano8060445 - 18 Jun 2018

Cited by 22 | Viewed by 4882

Abstract

In photodynamic therapy (PDT), chlorin e6 (Ce6), with its high phototoxic potential and strong absorption of visible light, penetrates deeply into photodamaged tissue. However, despite this fact, the direct application of Ce6 to PDT has been limited by its low water solubility and [...] Read more.

In photodynamic therapy (PDT), chlorin e6 (Ce6), with its high phototoxic potential and strong absorption of visible light, penetrates deeply into photodamaged tissue. However, despite this fact, the direct application of Ce6 to PDT has been limited by its low water solubility and poor cancer cell localization. To ameliorate this situation, we report herein on the use of a hydrophilic nanoconjugate (DC) comprised of Ce6 and poly(amidoamine) dendrimer, which improves the water solubility and intracellular uptake of Ce6, thereby enhancing PDT efficacy. The synthesis of DC was verified by ¹H nuclear magnetic resonance (NMR) analysis, and the coupling ratio of Ce6 introduced onto DC was 2.64. The prepared DC was spherical, with an average diameter of 61.7 ± 3.5 nm. In addition, the characteristic ultraviolet-visible absorption bands of DC in distilled water were similar to those of free Ce6 in dimethyl sulfoxide (DMSO), indicating that the Ce6 chromophore did not change upon conjugation. Investigation using fluorescence spectroscopy and confocal microscopy revealed a greater intracellular uptake of DC than of Ce6 alone. Moreover, DC exhibited significantly increased phototoxicity to human cervical cancer cells, mostly because of apoptotic cell death. These results imply that DC is a candidate for the clinical treatment of PDT. Full article

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12 pages, 4385 KiB

Open AccessArticle

In Situ Synthesis of Ag@Cu₂O-rGO Architecture for Strong Light-Matter Interactions

by Shuang Guo, Yaxin Wang, Fan Zhang, Renxian Gao, Maomao Liu, Lirong Dong, Yang Liu, Yongjun Zhang and Lei Chen

Nanomaterials 2018, 8(6), 444; https://doi.org/10.3390/nano8060444 - 17 Jun 2018

Cited by 10 | Viewed by 4514

Abstract

Emerging opportunities based on two-dimensional (2D) layered structures can utilize a variety of complex geometric architectures. Herein, we report the synthesis and properties of a 2D+0D unique ternary platform-core-shell nanostructure, termed Ag@Cu₂O-rGO, where the reduced graphene oxide (rGO) 2D acting as [...] Read more.

Emerging opportunities based on two-dimensional (2D) layered structures can utilize a variety of complex geometric architectures. Herein, we report the synthesis and properties of a 2D+0D unique ternary platform-core-shell nanostructure, termed Ag@Cu₂O-rGO, where the reduced graphene oxide (rGO) 2D acting as a platform is uniformly decorated by Ag@Cu₂O core-shell nanoparticles. Cu₂O nanoparticles occupy the defect positions on the surface of the rGO platform and restore the conjugation of the rGO structure, which contributes to the significant decrease of the I_D/I_G intensity ratio. The rGO platform can not only bridge the isolated nanoparticles together but also can quickly transfer the free electrons arising from the Ag core to the Cu₂O shell to improve the utilization efficiency of photogenerated electrons, as is verified by high efficient photocatalytic activity of Methyl Orange (MO). The multi-interface coupling of the Ag@Cu₂O-rGO platform-core-shell nanostructure leads to the decrease of the bandgap with an increase of the Cu₂O shell thickness, which broadens the absorption range of the visible light spectrum. Full article

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12 pages, 3633 KiB

Open AccessCommunication

Nitrogen-Doped Carbon Nanoparticles Derived from Silkworm Excrement as On–Off–On Fluorescent Sensors to Detect Fe(III) and Biothiols

by Xingchang Lu, Chen Liu, Zhimin Wang, Junyi Yang, Mengjing Xu, Jun Dong, Ping Wang, Jiangjiang Gu and Feifei Cao

Nanomaterials 2018, 8(6), 443; https://doi.org/10.3390/nano8060443 - 17 Jun 2018

Cited by 30 | Viewed by 4780

Abstract

On–off–on fluorescent sensors based on emerging carbon nanoparticles (CNPs) or carbon dots (CDs) have attracted extensive attention for their convenience and efficiency. In this study, dumped silkworm excrement was used as a novel precursor to prepare fluorescent nitrogen-doped CNPs (N-CNPs) through hydrothermal treatment. [...] Read more.

On–off–on fluorescent sensors based on emerging carbon nanoparticles (CNPs) or carbon dots (CDs) have attracted extensive attention for their convenience and efficiency. In this study, dumped silkworm excrement was used as a novel precursor to prepare fluorescent nitrogen-doped CNPs (N-CNPs) through hydrothermal treatment. The obtained N-CNPs showed good photoluminescent properties and excellent water dispersibility. Thus, they were applied as fluorescence “on–off–on” probes for the detection of Fe(III) and biothiols. The “on–off” process was achieved by adding Fe(III) into N-CNP solution, which resulted in the selective fluorescence quenching, with the detection limit of 0.20 μM in the linear range of 1–500 μM. Following this, the introduction of biothiols could recover the fluorescence efficiently, in order to realize the “off–on” process. By using glutathione (GSH) as the representative, the linear range was in the range of 1–1000 μM, and the limit of detection was 0.13 μM. Moreover, this useful strategy was successfully applied for the determination of amounts of GSH in fetal calf serum samples. Full article

(This article belongs to the Special Issue Nanostructured Biosensors)

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18 pages, 4007 KiB

Open AccessArticle

Emergence of Quantum Phase-Slip Behaviour in Superconducting NbN Nanowires: DC Electrical Transport and Fabrication Technologies

by Nicolas G. N. Constantino, Muhammad Shahbaz Anwar, Oscar W. Kennedy, Manyu Dang, Paul A. Warburton and Jonathan C. Fenton

Nanomaterials 2018, 8(6), 442; https://doi.org/10.3390/nano8060442 - 16 Jun 2018

Cited by 27 | Viewed by 4668

Abstract

Superconducting nanowires undergoing quantum phase-slips have potential for impact in electronic devices, with a high-accuracy quantum current standard among a possible toolbox of novel components. A key element of developing such technologies is to understand the requirements for, and control the production of, [...] Read more.

Superconducting nanowires undergoing quantum phase-slips have potential for impact in electronic devices, with a high-accuracy quantum current standard among a possible toolbox of novel components. A key element of developing such technologies is to understand the requirements for, and control the production of, superconducting nanowires that undergo coherent quantum phase-slips. We present three fabrication technologies, based on using electron-beam lithography or neon focussed ion-beam lithography, for defining narrow superconducting nanowires, and have used these to create nanowires in niobium nitride with widths in the range of 20–250 nm. We present characterisation of the nanowires using DC electrical transport at temperatures down to 300 mK. We demonstrate that a range of different behaviours may be obtained in different nanowires, including bulk-like superconducting properties with critical-current features, the observation of phase-slip centres and the observation of zero conductance below a critical voltage, characteristic of coherent quantum phase-slips. We observe critical voltages up to 5 mV, an order of magnitude larger than other reports to date. The different prominence of quantum phase-slip effects in the various nanowires may be understood as arising from the differing importance of quantum fluctuations. Control of the nanowire properties will pave the way for routine fabrication of coherent quantum phase-slip nanowire devices for technology applications. Full article

(This article belongs to the Special Issue Synthesis and Characterization of Nanowires)

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14 pages, 5629 KiB

Open AccessArticle

Synthesis of Magnetic Wood Fiber Board and Corresponding Multi-Layer Magnetic Composite Board, with Electromagnetic Wave Absorbing Properties

by Zhichao Lou, Yao Zhang, Ming Zhou, He Han, Jiabin Cai, Lintian Yang, Chenglong Yuan and Yanjun Li

Nanomaterials 2018, 8(6), 441; https://doi.org/10.3390/nano8060441 - 16 Jun 2018

Cited by 41 | Viewed by 4278

Abstract

With the rapid growth in the use of wireless electronic devices, society urgently needs electromagnetic wave (EMW) absorbing material with light weight, thin thickness, wide effective absorbing band width, and strong absorption capacity. Herein, the multi-layer magnetic composite boards are fabricated by hot-pressing [...] Read more.

With the rapid growth in the use of wireless electronic devices, society urgently needs electromagnetic wave (EMW) absorbing material with light weight, thin thickness, wide effective absorbing band width, and strong absorption capacity. Herein, the multi-layer magnetic composite boards are fabricated by hot-pressing magnetic fiber boards and normal veneer layer-by-layer. The magnetic fibers obtained using in-situ chemical co-precipitation are used to fabricate magnetic fiber board by hot-pressing. The magnetic wave absorbing capacities of the magnetic fiber boards obtained with 72 h impregnation time exhibit strongest adsorption capacities of −51.01 dB with a thickness of 3.00 mm. It is proved that this outstanding EMW absorption property is due to the strongest dielectric loss, the optimal magnetic loss, and the dipole relaxation polarization. Meanwhile, the EMW absorbing capacities of the corresponding multi-layer composite magnetic board increases from −14.14 dB (3-layer) to −60.16 dB (7-layer). This is due to the generated multi-interfaces between magnetic fiber board and natural wood veneer in the EMW propagation direction, which significantly benefit multireflection and attenuation of the incident waves. The results obtained in this work indicate that natural wood fibers are of great potential in the fabrication of magnetic multi-layer boards treated as EMW absorbers via a low cost, green, and scalable method. Full article

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14 pages, 5211 KiB

Open AccessArticle

Hazy Al₂O₃-FTO Nanocomposites: A Comparative Study with FTO-Based Nanocomposites Integrating ZnO and S:TiO₂ Nanostructures

by Shan-Ting Zhang, Guy Vitrant, Etienne Pernot, Carmen Jiménez, David Muñoz-Rojas and Daniel Bellet

Nanomaterials 2018, 8(6), 440; https://doi.org/10.3390/nano8060440 - 16 Jun 2018

Cited by 3 | Viewed by 4753

Abstract

In this study, we report the use of Al₂O₃ nanoparticles in combination with fluorine doped tin oxide (F:SnO₂, aka FTO) thin films to form hazy Al₂O₃-FTO nanocomposites. In comparison to previously reported FTO-based nanocomposites [...] Read more.

In this study, we report the use of Al₂O₃ nanoparticles in combination with fluorine doped tin oxide (F:SnO₂, aka FTO) thin films to form hazy Al₂O₃-FTO nanocomposites. In comparison to previously reported FTO-based nanocomposites integrating ZnO and sulfur doped TiO₂ (S:TiO₂) nanoparticles (i.e., ZnO-FTO and S:TiO₂-FTO nanocomposites), the newly developed Al₂O₃-FTO nanocomposites show medium haze factor H_T of about 30%, while they exhibit the least loss in total transmittance T_tot. In addition, Al₂O₃-FTO nanocomposites present a low fraction of large-sized nanoparticle agglomerates with equivalent radius r_eq > 1 μm; effectively 90% of the nanoparticle agglomerates show r_eq < 750 nm. The smaller feature size in Al₂O₃-FTO nanocomposites, as compared to ZnO-FTO and S:TiO₂-FTO nanocomposites, makes them more suitable for applications that are sensitive to roughness and large-sized features. With the help of a simple optical model developed in this work, we have simulated the optical scattering by a single nanoparticle agglomerate characterized by bottom radius r₀, top radius r₁, and height h. It is found that r₀ is the main factor affecting the H_T(λ), which indicates that the haze factor of Al₂O₃-FTO and related FTO nanocomposites is mainly determined by the total surface coverage of all the nanoparticle agglomerates present. Full article

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9 pages, 1849 KiB

Open AccessShort Note

Time-Dependent Growth of Silica Shells on CdTe Quantum Dots

by Pavlína Modlitbová, Karel Klepárník, Zdeněk Farka, Pavel Pořízka, Petr Skládal, Karel Novotný and Jozef Kaiser

Nanomaterials 2018, 8(6), 439; https://doi.org/10.3390/nano8060439 - 16 Jun 2018

Cited by 8 | Viewed by 3998

Abstract

The purpose of this study is to investigate the time dependent growth of silica shells on CdTe quantum dots to get their optimum thicknesses for practical applications. The core/shell structured silica-coated CdTe quantum dots (CdTe/SiO₂ QDs) were synthesized by the Ströber process, [...] Read more.

The purpose of this study is to investigate the time dependent growth of silica shells on CdTe quantum dots to get their optimum thicknesses for practical applications. The core/shell structured silica-coated CdTe quantum dots (CdTe/SiO₂ QDs) were synthesized by the Ströber process, which used CdTe QDs co-stabilized by mercaptopropionic acid. The coating procedure used silane primer (3-mercaptopropyltrimethoxysilane) in order to make the quantum dots (QDs) surface vitreophilic. The total size of QDs was dependent on both the time of silica shell growth in the presence of sodium silicate, and on the presence of ethanol during this growth. The size of particles was monitored during the first 72 h using two principally different methods: Dynamic Light Scattering (DLS), and Scanning Electron Microscopy (SEM). The data obtained by both methods were compared and reasons for differences discussed. Without ethanol precipitation, the silica shell thickness grew slowly and increased the nanoparticle total size from approximately 23 nm up to almost 30 nm (DLS data), and up to almost 60 nm (SEM data) in three days. During the same time period but in the presence of ethanol, the size of CdTe/SiO₂ QDs increased more significantly: up to 115 nm (DLS data) and up to 83 nm (SEM data). The variances occurring between silica shell thicknesses caused by different methods of silica growth, as well as by different evaluation methods, were discussed. Full article

(This article belongs to the Special Issue Preparation, Characterization and Utility of Quantum Dots)

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17 pages, 3121 KiB

Open AccessArticle

Functionalized Tyrosinase-Lignin Nanoparticles as Sustainable Catalysts for the Oxidation of Phenols

by Eliana Capecchi, Davide Piccinino, Ines Delfino, Paolo Bollella, Riccarda Antiochia and Raffaele Saladino

Nanomaterials 2018, 8(6), 438; https://doi.org/10.3390/nano8060438 - 15 Jun 2018

Cited by 37 | Viewed by 5772

Abstract

Sustainable catalysts for the oxidation of phenol derivatives under environmentally friendly conditions were prepared by the functionalization of lignin nanoparticles with tyrosinase. Lignin, the most abundant polyphenol in nature, is the main byproduct in the pulp and paper manufacturing industry and biorefinery. Tyrosinase [...] Read more.

Sustainable catalysts for the oxidation of phenol derivatives under environmentally friendly conditions were prepared by the functionalization of lignin nanoparticles with tyrosinase. Lignin, the most abundant polyphenol in nature, is the main byproduct in the pulp and paper manufacturing industry and biorefinery. Tyrosinase has been immobilized by direct adsorption, encapsulation, and layer-by-layer deposition, with or without glutaraldehyde reticulation. Lignin nanoparticles were found to be stable to the tyrosinase activity. After the enzyme immobilization, they showed a moderate to high catalytic effect in the synthesis of catechol derivatives, with the efficacy of the catalyst being dependent on the specific immobilization procedures. Full article

(This article belongs to the Special Issue Sustainable Nanoparticles - Their Synthesis and Catalytic Applications)

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12 pages, 2981 KiB

Open AccessFeature PaperArticle

Stable and High Piezoelectric Output of GaN Nanowire-Based Lead-Free Piezoelectric Nanogenerator by Suppression of Internal Screening

by Muhammad Ali Johar, Mostafa Afifi Hassan, Aadil Waseem, Jun-Seok Ha, June Key Lee and Sang-Wan Ryu

Nanomaterials 2018, 8(6), 437; https://doi.org/10.3390/nano8060437 - 14 Jun 2018

Cited by 38 | Viewed by 5142

Abstract

A piezoelectric nanogenerator (PNG) that is based on c-axis GaN nanowires is fabricated on flexible substrate. In this regard, c-axis GaN nanowires were grown on GaN substrate using the vapor-liquid-solid (VLS) technique by metal organic chemical vapor deposition. Further, Polydimethylsiloxane (PDMS) was coated [...] Read more.

A piezoelectric nanogenerator (PNG) that is based on c-axis GaN nanowires is fabricated on flexible substrate. In this regard, c-axis GaN nanowires were grown on GaN substrate using the vapor-liquid-solid (VLS) technique by metal organic chemical vapor deposition. Further, Polydimethylsiloxane (PDMS) was coated on nanowire-arrays then PDMS matrix embedded with GaN nanowire-arrays was transferred on Si-rubber substrate. The piezoelectric performance of nanowire-based flexible PNG was measured, while the device was actuated using a cyclic stretching-releasing agitation mechanism that was driven by a linear motor. The piezoelectric output was measured as a function of actuation frequency ranging from 1 Hz to 10 Hz and a linear tendency was observed for piezoelectric output current, while the output voltages remained constant. A maximum of piezoelectric open circuit voltages and short circuit current were measured 15.4 V and 85.6 nA, respectively. In order to evaluate the feasibility of our flexible PNG for real application, a long term stability test was performed for 20,000 cycles and the device performance was degraded by less than 18%. The underlying reason for the high piezoelectric output was attributed to the reduced free carriers inside nanowires due to surface Fermi-level pinning and insulating metal-dielectric-semiconductor interface, respectively; the former reduced the free carrier screening radially while latter reduced longitudinally. The flexibility and the high aspect ratio of GaN nanowire were the responsible factors for higher stability. Such higher piezoelectric output and the novel design make our device more promising for the diverse range of real applications. Full article

(This article belongs to the Special Issue 1D Nanostructure-Based Piezo-Generators)

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8 pages, 1626 KiB

Open AccessArticle

Ag Nanotwin-Assisted Grain Growth-Induced by Stress in SiO₂/Ag/SiO₂ Nanocap Arrays

by Fan Zhang, Yaxin Wang, Yongjun Zhang, Lei Chen, Yang Liu and Jinghai Yang

Nanomaterials 2018, 8(6), 436; https://doi.org/10.3390/nano8060436 - 14 Jun 2018

Cited by 5 | Viewed by 3164

Abstract

A trilayer SiO₂/Ag/SiO₂ nanocap array was prepared on a two-dimensional template. When annealed at different temperatures, the curvature of the SiO₂/Ag/SiO₂ nanocap arrays increased, which led to Ag nanocap shrinkage. The stress provided by the curved SiO [...] Read more.

A trilayer SiO₂/Ag/SiO₂ nanocap array was prepared on a two-dimensional template. When annealed at different temperatures, the curvature of the SiO₂/Ag/SiO₂ nanocap arrays increased, which led to Ag nanocap shrinkage. The stress provided by the curved SiO₂ layer induced the formation of Ag nanotwins. Ag nanotwins assisted the growth of nanoparticles when the neighboring nanotwins changed the local misorientations. Nanocap shrinkage reduced the surface plasmon resonance (SPR) coupling between neighboring nanocaps; concurrently, grain growth decreased the SPR coupling between the particles in each nanocap, which led to a red shift of the localized surface plasmon resonance (LSPR) bands and decreased the surface-enhanced Raman scattering (SERS) signals. Full article

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17 pages, 4504 KiB

Open AccessArticle

Gelled Electrolyte Containing Phosphonium Ionic Liquids for Lithium-Ion Batteries

by Mélody Leclère, Laurent Bernard, Sébastien Livi, Michel Bardet, Armel Guillermo, Lionel Picard and Jannick Duchet-Rumeau

Nanomaterials 2018, 8(6), 435; https://doi.org/10.3390/nano8060435 - 14 Jun 2018

Cited by 17 | Viewed by 4640

Abstract

In this work, new gelled electrolytes were prepared based on a mixture containing phosphonium ionic liquid (IL) composed of trihexyl(tetradecyl)phosphonium cation combined with bis(trifluoromethane)sulfonimide [TFSI] counter anions and lithium salt, confined in a host network made from an epoxy prepolymer and amine hardener. [...] Read more.

In this work, new gelled electrolytes were prepared based on a mixture containing phosphonium ionic liquid (IL) composed of trihexyl(tetradecyl)phosphonium cation combined with bis(trifluoromethane)sulfonimide [TFSI] counter anions and lithium salt, confined in a host network made from an epoxy prepolymer and amine hardener. We have demonstrated that the addition of electrolyte plays a key role on the kinetics of polymerization but also on the final properties of epoxy networks, especially thermal, thermo-mechanical, transport, and electrochemical properties. Thus, polymer electrolytes with excellent thermal stability (>300 °C) combined with good thermo-mechanical properties have been prepared. In addition, an ionic conductivity of 0.13 Ms·cm⁻¹ at 100 °C was reached. Its electrochemical stability was 3.95 V vs. Li⁰/Li⁺ and the assembled cell consisting in Li|LiFePO₄ exhibited stable cycle properties even after 30 cycles. These results highlight a promising gelled electrolyte for future lithium ion batteries. Full article

(This article belongs to the Special Issue Polymers and Ionic Liquids: Shaping up a New Generation of High Performances Nanomaterials)

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26 pages, 6345 KiB

Open AccessArticle

Applications of Nanomaterials Based on Magnetite and Mesoporous Silica on the Selective Detection of Zinc Ion in Live Cell Imaging

by Roghayeh Sadeghi Erami, Karina Ovejero, Soraia Meghdadi, Marco Filice, Mehdi Amirnasr, Antonio Rodríguez-Diéguez, María Ulagares De La Orden and Santiago Gómez-Ruiz

Nanomaterials 2018, 8(6), 434; https://doi.org/10.3390/nano8060434 - 14 Jun 2018

Cited by 19 | Viewed by 5589

Abstract

Functionalized magnetite nanoparticles (FMNPs) and functionalized mesoporous silica nanoparticles (FMSNs) were synthesized by the conjugation of magnetite and mesoporous silica with the small and fluorogenic benzothiazole ligand, that is, 2(2-hydroxyphenyl)benzothiazole (hpbtz). The synthesized fluorescent nanoparticles were characterized by FTIR, XRD, XRF, [...] Read more.

Functionalized magnetite nanoparticles (FMNPs) and functionalized mesoporous silica nanoparticles (FMSNs) were synthesized by the conjugation of magnetite and mesoporous silica with the small and fluorogenic benzothiazole ligand, that is, 2(2-hydroxyphenyl)benzothiazole (hpbtz). The synthesized fluorescent nanoparticles were characterized by FTIR, XRD, XRF, ¹³C CP MAS NMR, BET, and TEM. The photophysical behavior of FMNPs and FMSNs in ethanol was studied using fluorescence spectroscopy. The modification of magnetite and silica scaffolds with the highly fluorescent benzothiazole ligand enabled the nanoparticles to be used as selective and sensitive optical probes for zinc ion detection. Moreover, the presence of hpbtz in FMNPs and FMSNs induced efficient cell viability and zinc ion uptake, with desirable signaling in the normal human kidney epithelial (Hek293) cell line. The significant viability of FMNPs and FMSNs (80% and 92%, respectively) indicates a potential applicability of these nanoparticles as in vitro imaging agents. The calculated limit of detections (LODs) were found to be 2.53 × 10⁻⁶ and 2.55 × 10⁻⁶ M for Fe₃O₄-H@hpbtz and MSN-Et₃N-IPTMS-hpbtz-f1, respectively. FMSNs showed more pronounced zinc signaling relative to FMNPs, as a result of the more efficient penetration into the cells. Full article

(This article belongs to the Special Issue Nanostructured Biosensors)

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13 pages, 1970 KiB

Open AccessArticle

Construction of Hyaluronic Tetrasaccharide Clusters Modified Polyamidoamine siRNA Delivery System

by Yingcong Ma, Meng Sha, Shixuan Cheng, Wang Yao, Zhongjun Li and Xian-Rong Qi

Nanomaterials 2018, 8(6), 433; https://doi.org/10.3390/nano8060433 - 14 Jun 2018

Cited by 12 | Viewed by 3546

Abstract

The CD44 protein, as a predominant receptor for hyaluronan (HA), is highly expressed on the surface of multiple tumor cells. HA, as a targeting molecule for a CD44-contained delivery system, increases intracellular drug concentration in tumor tissue. However, due to the weak binding [...] Read more.

The CD44 protein, as a predominant receptor for hyaluronan (HA), is highly expressed on the surface of multiple tumor cells. HA, as a targeting molecule for a CD44-contained delivery system, increases intracellular drug concentration in tumor tissue. However, due to the weak binding ability of hyaluronan oligosaccharide to CD44, targeting for tumor drug delivery has been restricted. In this study, we first use a HA tetrasaccharide cluster as the target ligand to enhance the binding ability to CD44. A polyamidoamine (PAMAM) dendrimer was modified by a HA tetrasaccharide cluster as a nonviral vector for small interfering RNA (siRNA) delivery. The dendrimer/siRNA nanocomplexes increased the cellular uptake capacity of siRNA through the CD44 receptor-mediated endocytosis pathway, allowing the siRNA to successfully escape the endosome/lysosome. Compared with the control group, nanocomplexes effectively reduced the expression of GFP protein and mRNA in MDA-MB-231-GFP cells. This delivery system provides a foundation to increase the clinical applications of PAMAM nanomaterials. Full article

(This article belongs to the Special Issue Pharmaceutical Nanotechnology)

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16 pages, 3669 KiB

Open AccessArticle

Carbon Nitride Materials as Efficient Catalyst Supports for Proton Exchange Membrane Water Electrolyzers

by Ana Belen Jorge, Ishanka Dedigama, Thomas S. Miller, Paul Shearing, Daniel J. L. Brett and Paul F. McMillan

Nanomaterials 2018, 8(6), 432; https://doi.org/10.3390/nano8060432 - 13 Jun 2018

Cited by 18 | Viewed by 5043

Abstract

Carbon nitride materials with graphitic to polymeric structures (gCNH) were investigated as catalyst supports for the proton exchange membrane (PEM) water electrolyzers using IrO₂ nanoparticles as oxygen evolution electrocatalyst. Here, the performance of IrO₂ nanoparticles formed and deposited in situ onto [...] Read more.

Carbon nitride materials with graphitic to polymeric structures (gCNH) were investigated as catalyst supports for the proton exchange membrane (PEM) water electrolyzers using IrO₂ nanoparticles as oxygen evolution electrocatalyst. Here, the performance of IrO₂ nanoparticles formed and deposited in situ onto carbon nitride support for PEM water electrolysis was explored based on previous preliminary studies conducted in related systems. The results revealed that this preparation route catalyzed the decomposition of the carbon nitride to form a material with much lower N content. This resulted in a significant enhancement of the performance of the gCNH-IrO₂ (or N-doped C-IrO₂) electrocatalyst that was likely attributed to higher electrical conductivity of the N-doped carbon support. Full article

(This article belongs to the Special Issue Graphitic Carbon Nitride Nanostructures: Catalysis and Beyond)

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9 pages, 3491 KiB

Open AccessArticle

Preparation of TiO₂/Carbon Nanotubes/Reduced Graphene Oxide Composites with Enhanced Photocatalytic Activity for the Degradation of Rhodamine B

by Yanzhen Huang, Dongping Chen, Xinling Hu, Yingjiang Qian and Dongxu Li

Nanomaterials 2018, 8(6), 431; https://doi.org/10.3390/nano8060431 - 13 Jun 2018

Cited by 58 | Viewed by 8405

Abstract

In this report, ternary titanium dioxide (TiO₂)/carbon nanotubes (CNTs)/reduced graphene oxide (rGO) composites were fabricated by a facile and environmentally friendly one-pot solvethermal method for the removal of Rhodamine B (RhB). Its structures were represented by X-ray powder diffraction (XRD), Raman [...] Read more.

In this report, ternary titanium dioxide (TiO₂)/carbon nanotubes (CNTs)/reduced graphene oxide (rGO) composites were fabricated by a facile and environmentally friendly one-pot solvethermal method for the removal of Rhodamine B (RhB). Its structures were represented by X-ray powder diffraction (XRD), Raman spectrometry, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The photocatalytic performance was tested by the degradation efficiency of RhB under UV-vis light irradiation. The experimental results indicated that photocatalytic activity improved as the ratio of CNTs:TiO₂ ranged from 0.5% to 3% but reduced when the content increased to 5% and 10%, and the TiO₂/CNTs/rGO-3% composites showed superior photocatalytic activity compared with the binary ones (i.e., TiO₂/CNTs, TiO₂/rGO) and pristine TiO₂. The rate constant k of the pseudo first-order reaction was about 1.5 times that of TiO₂. The improved photocatalytic activity can be attributed to the addition of rGO and CNTs, which reduced the recombination of photo-induced electron-hole pairs, and the fact that CNTs and rGO, with a high specific surface area and high adsorption ability to efficiently adsorb O₂, H₂O and organics, can increase the hydroxyl content of the photocatalyst surface. Full article

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15 pages, 6664 KiB

Open AccessArticle

Easy Synthesis and Characterization of Holmium-Doped SPIONs

by Magdalena Osial, Paulina Rybicka, Marek Pękała, Grzegorz Cichowicz, Michał K. Cyrański and Paweł Krysiński

Nanomaterials 2018, 8(6), 430; https://doi.org/10.3390/nano8060430 - 13 Jun 2018

Cited by 29 | Viewed by 4558

Abstract

The exceptional magnetic properties of superparamagnetic iron oxide nanoparticles (SPIONs) make them promising materials for biomedical applications like hyperthermia, drug targeting and imaging. Easy preparation of SPIONs with the controllable, well-defined properties is a key factor of their practical application. In this work, [...] Read more.

The exceptional magnetic properties of superparamagnetic iron oxide nanoparticles (SPIONs) make them promising materials for biomedical applications like hyperthermia, drug targeting and imaging. Easy preparation of SPIONs with the controllable, well-defined properties is a key factor of their practical application. In this work, we report a simple synthesis of Ho-doped SPIONs by the co-precipitation route, with controlled size, shape and magnetic properties. To investigate the influence of the ions ratio on the nanoparticles’ properties, multiple techniques were used. Powder X-ray diffraction (PXRD) confirmed the crystallographic structure, indicating formation of an Fe₃O₄ core doped with holmium. In addition, transmission electron microscopy (TEM) confirmed the correlation of the crystallites’ shape and size with the experimental conditions, pointing to critical holmium content around 5% for the preparation of uniformly shaped grains, while larger holmium content leads to uniaxial growth with a prism shape. Studies of the magnetic behaviour of nanoparticles show that magnetization varies with changes in the initial Ho³⁺ ions percentage during precipitation, while below 5% of Ho in doped Fe₃O₄ is relatively stable and sufficient for biomedicine applications. The characterization of prepared nanoparticles suggests that co-precipitation is a simple and efficient technique for the synthesis of superparamagnetic, Ho-doped SPIONs for hyperthermia application. Full article

(This article belongs to the Special Issue Nanocolloids for Nanomedicine and Drug Delivery)

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14 pages, 4557 KiB

Open AccessArticle

Copper Nanoparticle and Nitrogen Doped Graphite Oxide Based Biosensor for the Sensitive Determination of Glucose

by Kulandaivel Sivasankar, Karuppasamy Kohila Rani, Sea-Fue Wang, Rajkumar Devasenathipathy and Chia-Her Lin

Nanomaterials 2018, 8(6), 429; https://doi.org/10.3390/nano8060429 - 13 Jun 2018

Cited by 16 | Viewed by 5345

Abstract

Copper nanoparticles with the diameter of 50 ± 20 nm decorated nitrogen doped graphite oxide (NGO) have been prepared through a simple single step carbonization method using copper metal-organic framework (MOF), [Cu₂(BDC)₂(DABCO)] (where BDC is 1,4-benzenedicarboxylate, and DABCO is [...] Read more.

Copper nanoparticles with the diameter of 50 ± 20 nm decorated nitrogen doped graphite oxide (NGO) have been prepared through a simple single step carbonization method using copper metal-organic framework (MOF), [Cu₂(BDC)₂(DABCO)] (where BDC is 1,4-benzenedicarboxylate, and DABCO is 1,4-Diazabicyclo[2.2.2]octane) as precursor. The surface morphology, porosity, surface area and elemental composition of CuNPs/NGO were characterized by various techniques. The as-synthesized CuNPs/NGO nanomaterials were coated on commercially available disposable screen-printed carbon electrode for the sensitive determination of glucose. We find that the modified electrode can detect glucose between 1 μM and 1803 μM (linear range) with good sensitivity (2500 μA mM⁻¹ cm⁻²). Our glucose sensor also possesses low limits of detection (0.44 μM) towards glucose determination. The highly selective nature of the fabricated electrode was clearly visible from the selectivity studies. The practicability of CuNPs/NGO modified electrode has been validated in the human serum samples. The storage stability along with better repeatability and reproducibility results additionally substantiate the superior electrocatalytic activity of our constructed sensor towards glucose. Full article

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11 pages, 1992 KiB

Open AccessArticle

Optimization of Malachite Green Removal from Water by TiO₂ Nanoparticles under UV Irradiation

by Yongmei Ma, Maofei Ni and Siyue Li

Nanomaterials 2018, 8(6), 428; https://doi.org/10.3390/nano8060428 - 13 Jun 2018

Cited by 44 | Viewed by 4310

Abstract

TiO₂ nanoparticles with surface porosity were prepared by a simple and efficient method and presented for the removal of malachite green (MG), a representative organic pollutant, from aqueous solution. Photocatalytic degradation experiments were systematically conducted to investigate the influence of TiO₂ [...] Read more.

TiO₂ nanoparticles with surface porosity were prepared by a simple and efficient method and presented for the removal of malachite green (MG), a representative organic pollutant, from aqueous solution. Photocatalytic degradation experiments were systematically conducted to investigate the influence of TiO₂ dosage, pH value, and initial concentrations of MG. The kinetics of the reaction were monitored via UV spectroscopy and the kinetic process can be well predicted by the pseudo first-order model. The rate constants of the reaction kinetics were found to decrease as the initial MG concentration increased; increased via elevated pH value at a certain amount of TiO₂ dosage. The maximum efficiency of photocatalytic degradation was obtained when the TiO₂ dosage, pH value and initial concentrations of MG were 0.6 g/L, 8 and 10⁻⁵ mol/L (M), respectively. Results from this study provide a novel optimization and an efficient strategy for water pollutant treatment. Full article

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13 pages, 3062 KiB

Open AccessArticle

Construction of g-C₃N₄-mNb₂O₅ Composites with Enhanced Visible Light Photocatalytic Activity

by Meiyin Wang, Hui Wang, Yuanhang Ren, Cheng Wang, Zhewei Weng, Bin Yue and Heyong He

Nanomaterials 2018, 8(6), 427; https://doi.org/10.3390/nano8060427 - 12 Jun 2018

Cited by 15 | Viewed by 3822

Abstract

A series of composites consisting of g-C₃N₄ sheet and mesoporous Nb₂O₅ (mNb₂O₅) microsphere were fabricated by in situ hydrolysis deposition of NbCl₅ onto g-C₃N₄ sheet followed by solvothermal treatment. [...] Read more.

A series of composites consisting of g-C₃N₄ sheet and mesoporous Nb₂O₅ (mNb₂O₅) microsphere were fabricated by in situ hydrolysis deposition of NbCl₅ onto g-C₃N₄ sheet followed by solvothermal treatment. The samples were characterized using powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), N₂ adsorption-desorption, X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (DRS) and photoluminescence spectroscopy (PL). The photocatalytic activity of the composites was studied by degradation of rhodamine B (RhB) and tetracycline hydrochloride (TC-HCl) in aqueous solution under visible light irradiation (λ > 420 nm). Compared with g-C₃N₄ and mNb₂O₅, g-C₃N₄-mNb₂O₅ composites have higher photocatalytic activity due to synergistic effect between g-C₃N₄ and mNb₂O₅. Among these composites, 4% g-C₃N₄-mNb₂O₅ has the highest efficiency and good recyclability for degradation of both RhB and TC-HCl. Full article

(This article belongs to the Special Issue Synthesis and Applications of Nanomaterials for Photocatalysis and Electrocatalysis)

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16 pages, 4661 KiB

Open AccessFeature PaperArticle

Piezo-Potential Generation in Capacitive Flexible Sensors Based on GaN Horizontal Wires

by Amine El Kacimi, Emmanuelle Pauliac-Vaujour, Olivier Delléa and Joël Eymery

Nanomaterials 2018, 8(6), 426; https://doi.org/10.3390/nano8060426 - 12 Jun 2018

Cited by 5 | Viewed by 3700

Abstract

We report an example of the realization of a flexible capacitive piezoelectric sensor based on the assembly of horizontal

\bar{c}

-polar long Gallium nitride (GaN) wires grown by metal organic vapour phase epitaxy (MOVPE) with the Boostream^® technique spreading wires on [...] Read more.

We report an example of the realization of a flexible capacitive piezoelectric sensor based on the assembly of horizontal

\bar{c}

-polar long Gallium nitride (GaN) wires grown by metal organic vapour phase epitaxy (MOVPE) with the Boostream^® technique spreading wires on a moving liquid before their transfer on large areas. The measured signal (<0.6 V) obtained by a punctual compression/release of the device shows a large variability attributed to the dimensions of the wires and their in-plane orientations. The cause of this variability and the general operating mechanisms of this flexible capacitive device are explained by finite element modelling simulations. This method allows considering the full device composed of a metal/dielectric/wires/dielectric/metal stacking. We first clarify the mechanisms involved in the piezo-potential generation by mapping the charge and piezo-potential in a single wire and studying the time-dependent evolution of this phenomenon. GaN wires have equivalent dipoles that generate a tension between metallic electrodes only when they have a non-zero in-plane projection. This is obtained in practice by the conical shape occurring spontaneously during the MOVPE growth. The optimal aspect ratio in terms of length and conicity (for the usual MOVPE wire diameter) is determined for a bending mechanical loading. It is suggested to use 60–120 µm long wires (i.e., growth time less than 1 h). To study further the role of these dipoles, we consider model systems with in-plane 1D and 2D regular arrays of horizontal wires. It is shown that a strong electrostatic coupling and screening occur between neighbouring horizontal wires depending on polarity and shape. This effect, highlighted here only from calculations, should be taken into account to improve device performance. Full article

(This article belongs to the Special Issue 1D Nanostructure-Based Piezo-Generators)

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13 pages, 4992 KiB

Open AccessArticle

Mesoscopic Modeling of the Encapsulation of Capsaicin by Lecithin/Chitosan Liposomal Nanoparticles

by Ketzasmin A. Terrón-Mejía, Evelin Martínez-Benavidez, Inocencio Higuera-Ciapara, Claudia Virués, Javier Hernández, Zaira Domínguez, Waldo Argüelles-Monal, Francisco M. Goycoolea, Roberto López-Rendón and Armando Gama Goicochea

Nanomaterials 2018, 8(6), 425; https://doi.org/10.3390/nano8060425 - 12 Jun 2018

Cited by 14 | Viewed by 5328

Abstract

The transport of hydrophobic drugs in the human body exhibits complications due to the low solubility of these compounds. With the purpose of enhancing the bioavailability and biodistribution of such drugs, recent studies have reported the use of amphiphilic molecules, such as phospholipids, [...] Read more.

The transport of hydrophobic drugs in the human body exhibits complications due to the low solubility of these compounds. With the purpose of enhancing the bioavailability and biodistribution of such drugs, recent studies have reported the use of amphiphilic molecules, such as phospholipids, for the synthesis of nanoparticles or nanocapsules. Given that phospholipids can self-assemble in liposomes or micellar structures, they are ideal candidates to function as vehicles of hydrophobic molecules. In this work, we report mesoscopic simulations of nanoliposomes, constituted by lecithin and coated with a shell of chitosan. The stability of such structures and the efficiency of the encapsulation of capsaicin, as well as the internal and superficial distribution of capsaicin and chitosan inside the nanoliposome, were analyzed. The characterization of the system was carried out through density maps and the potentials of mean force for the lecithin-capsaicin, lecithin-chitosan, and capsaicin-chitosan interactions. The results of these simulations show that chitosan is deposited on the surface of the nanoliposome, as has been reported in some experimental works. It was also observed that a nanoliposome of approximately 18 nm in diameter is stable during the simulation. The deposition behavior was found to be influenced by a pattern of N-acetylation of chitosan. Full article

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9 pages, 2752 KiB

Open AccessArticle

Complex Magnetization Harmonics of Polydispersive Magnetic Nanoclusters

by Suko Bagus Trisnanto and Yasushi Takemura

Nanomaterials 2018, 8(6), 424; https://doi.org/10.3390/nano8060424 - 11 Jun 2018

Cited by 7 | Viewed by 3854

Abstract

Understanding magnetic interparticle interactions within a single hydrodynamic volume of polydispersed magnetic nanoparticles and the resulting nonlinear magnetization properties is critical for their implementation in magnetic theranostics. However, in general, the field-dependent static and dynamic magnetization measurements may only highlight polydispersity effects including [...] Read more.

Understanding magnetic interparticle interactions within a single hydrodynamic volume of polydispersed magnetic nanoparticles and the resulting nonlinear magnetization properties is critical for their implementation in magnetic theranostics. However, in general, the field-dependent static and dynamic magnetization measurements may only highlight polydispersity effects including magnetic moment and size distributions. Therefore, as a complement to such typical analysis of hysteretic magnetization curves, we spectroscopically examined the complex magnetization harmonics of magnetic nanoclusters either dispersed in a liquid medium or immobilized by a hydrocolloid polymer, later to emphasize the harmonic characteristics for different core sizes. In the case of superparamagnetic nanoclusters with a 4-nm primary size, particularly, we correlated the negative quadrature components of the third-harmonic susceptibility with an insignificant cluster rotation induced by the oscillatory field. Moreover, the field-dependent in-phase components appear to be frequency-independent, suggesting a weak damping effect on the moment dynamics. The characteristic of the Néel time constant further supports this argument by showing a smaller dependence on the applied dc bias field, in comparison to that of larger cores. These findings show that the complex harmonic components of the magnetization are important attributes to the interacting cores of a magnetic nanocluster. Full article

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13 pages, 2636 KiB

Open AccessArticle

Facet-Dependent Cuprous Oxide Nanocrystals Decorated with Graphene as Durable Photocatalysts under Visible Light

by Shou-Heng Liu and Jun-Sheng Lu

Nanomaterials 2018, 8(6), 423; https://doi.org/10.3390/nano8060423 - 11 Jun 2018

Cited by 10 | Viewed by 3437

Abstract

Three morphologies (octahedral, hierarchical and rhombic dodecahedral) of crystal Cu₂O with different facets ({111}, {111}/{110}, and {110}) incorporating graphene sheets (denoted as o-Cu₂O-G, h-Cu₂O-G and r-Cu₂O-G, respectively) have been fabricated by using simple solution-phase techniques. [...] Read more.

Three morphologies (octahedral, hierarchical and rhombic dodecahedral) of crystal Cu₂O with different facets ({111}, {111}/{110}, and {110}) incorporating graphene sheets (denoted as o-Cu₂O-G, h-Cu₂O-G and r-Cu₂O-G, respectively) have been fabricated by using simple solution-phase techniques. Among these photocatalysts, the r-Cu₂O-G possesses the best photocatalytic performance of 98% removal efficiency of methyl orange (MO) with outstanding kinetics for 120 min of visible light irradiation. This enhancement is mainly due to the dangling “Cu” atoms in the highly active {110} facets, resulting in the increased adsorption of negatively charged MO. More importantly, the unique interfacial structures of Cu₂O rhombic dodecahedra connected to graphene nanosheets can not only decrease the recombination of electron-hole pairs but also stabilize the crystal structure of Cu₂O, as verified by a series of spectroscopic analyses (e.g., X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM)). The effective photocatalysts developed in this work could be applied to the efficient decolorization of negatively charged organic dyes by employing solar energy. Full article

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10 pages, 3593 KiB

Open AccessArticle

A Thin Film Flexible Supercapacitor Based on Oblique Angle Deposited Ni/NiO Nanowire Arrays

by Jing Ma, Wen Liu, Shuyuan Zhang, Zhe Ma, Peishuai Song, Fuhua Yang and Xiaodong Wang

Nanomaterials 2018, 8(6), 422; https://doi.org/10.3390/nano8060422 - 11 Jun 2018

Cited by 16 | Viewed by 4998

Abstract

With high power density, fast charging-discharging speed, and a long cycling life, supercapacitors are a kind of highly developed novel energy-storage device that has shown a growing performance and various unconventional shapes such as flexible, linear-type, stretchable, self-healing, etc. Here, we proposed a [...] Read more.

With high power density, fast charging-discharging speed, and a long cycling life, supercapacitors are a kind of highly developed novel energy-storage device that has shown a growing performance and various unconventional shapes such as flexible, linear-type, stretchable, self-healing, etc. Here, we proposed a rational design of thin film, flexible micro-supercapacitors with in-plane interdigital electrodes, where the electrodes were fabricated using the oblique angle deposition technique to grow oblique Ni/NiO nanowire arrays directly on polyimide film. The obtained electrodes have a high specific surface area and good adhesion to the substrate compared with other in-plane micro-supercapacitors. Meanwhile, the as-fabricated micro-supercapacitors have good flexibility and satisfactory energy-storage performance, exhibiting a high specific capacity of 37.1 F/cm³, a high energy density of 5.14 mWh/cm³, a power density of up to 0.5 W/cm³, and good stability during charge-discharge cycles and repeated bending-recovery cycles, respectively. Our micro-supercapacitors can be used as ingenious energy storage devices for future portable and wearable electronic applications. Full article

(This article belongs to the Special Issue Metallic Nanostructures)

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16 pages, 7423 KiB

Open AccessArticle

Interfacial Model and Characterization for Nanoscale ReB₂/TaN Multilayers at Desired Modulation Period and Ratios: First-Principles Calculations and Experimental Investigations

by Shangxiao Jin and Dejun Li

Nanomaterials 2018, 8(6), 421; https://doi.org/10.3390/nano8060421 - 10 Jun 2018

Cited by 3 | Viewed by 3386

Abstract

The interfacial structure of ReB₂/TaN multilayers at varied modulation periods (Λ) and modulation ratios (t_ReB2:t_TaN) was investigated using key experiments combined with first-principles calculations. A maximum hardness of 38.7 GPa occurred at Λ [...] Read more.

The interfacial structure of ReB₂/TaN multilayers at varied modulation periods (Λ) and modulation ratios (t_ReB2:t_TaN) was investigated using key experiments combined with first-principles calculations. A maximum hardness of 38.7 GPa occurred at Λ = 10 nm and t_ReB2:t_TaN = 1:1. The fine nanocrystalline structure with small grain sizes remained stable for individual layers at Λ= 10 nm and t_ReB2:t_TaN = 1:1. The calculation of the interfacial structure model and interfacial energy was performed using the first principles to advance the in-depth understanding of the relationship between the mechanical properties, residual stresses, and the interfacial structure. The B-Ta interfacial configuration was calculated to have the highest adsorption energy and the lowest interfacial energy. The interfacial energy and adsorption energy at different t_ReB2:t_TaN followed the same trend as that of the residual stress. The 9ReB₂/21TaN interfacial structure in the B-Ta interfacial configuration was found to be the most stable interface in which the highest adsorption energy and the lowest interfacial energy were obtained. The chemical bonding between the neighboring B atom and the Ta atom in the interfaces showed both covalency and iconicity, which provided a theoretical interpretation of the relationship between the residual stress and the stable interfacial structure of the ReB₂/TaN multilayer. Full article

(This article belongs to the Special Issue Design and Development of Nanostructured Thin Films)

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13 pages, 12952 KiB

Open AccessArticle

Piezoelectric Response of Aligned Electrospun Polyvinylidene Fluoride/Carbon Nanotube Nanofibrous Membranes

by Chang-Mou Wu, Min-Hui Chou and Wun-Yuan Zeng

Nanomaterials 2018, 8(6), 420; https://doi.org/10.3390/nano8060420 - 10 Jun 2018

Cited by 114 | Viewed by 7119

Abstract

Polyvinylidene fluoride (PVDF) shows piezoelectricity related to its β-phase content and mechanical and electrical properties influenced by its morphology and crystallinity. Electrospinning (ES) can produce ultrafine and well-aligned PVDF nanofibers. In this study, the effects of the presence of carbon nanotubes (CNT) and [...] Read more.

Polyvinylidene fluoride (PVDF) shows piezoelectricity related to its β-phase content and mechanical and electrical properties influenced by its morphology and crystallinity. Electrospinning (ES) can produce ultrafine and well-aligned PVDF nanofibers. In this study, the effects of the presence of carbon nanotubes (CNT) and optimized ES parameters on the crystal structures and piezoelectric properties of aligned PVDF/CNT nanofibrous membranes were examined. The optimal β content and piezoelectric coefficient (d₃₃) of the aligned electrospun PVDF reached 88% and 27.4 pC/N; CNT addition increased the β-phase content to 89% and d₃₃ to 31.3 pC/N. The output voltages of piezoelectric units with aligned electrospun PVDF/CNT membranes increased linearly with applied loading and showed good stability during cyclic dynamic compression and tension. The sensitivities of the piezoelectric units with the membranes under dynamic compression and tension were 2.26 mV/N and 4.29 mV/%, respectively. In bending tests, the output voltage increased nonlinearly with bending angle because complicated forces were involved. The output of the aligned membrane-based piezoelectric unit with CNT was 1.89 V at the bending angle of 100°. The high electric outputs indicate that the aligned electrospun PVDF/CNT membranes are potentially effective for flexible wearable sensor application with high sensitivity. Full article

(This article belongs to the Special Issue Smart Nanogenerators)

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