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Nanomaterials, Volume 12, Issue 22 (November-2 2022) – 181 articles

Cover Story (view full-size image): The ability to confine light in extremely small dimensions is critical in imaging, biosensing, lasing and other applications. Hyperbolic media metamaterials are a promising means by which to achieve these applications owing to their open-curved hyperbolic dispersion. An indefinite cavity formed by graphene hyperbolic media metamaterials has an ultra-compressed mode volume confinement factor one billion times smaller than the free-space wavelength volume and anomalous scaling rules of a conventional optical cavity. An ultrahigh refractive index of up to nearly three hundred can be realized. The proposed cavity opens a new door allowing light to be condensed down to the nanometric scale, providing a platform with which to explore ultra-strong light–matter interactions at mid-infrared to terahertz spectral ranges. View this paper
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11 pages, 2458 KiB  
Article
All-Optical Nanosensor for Displacement Detection in Mechanical Applications
by Lorena Escandell, Carlos Álvarez-Rodríguez, Ángela Barreda, Ramón Zaera and Braulio García-Cámara
Nanomaterials 2022, 12(22), 4107; https://doi.org/10.3390/nano12224107 - 21 Nov 2022
Viewed by 1419
Abstract
In this paper, we propose the design of an optical system based on two parallel suspended silicon nanowires that support a range of optical resonances that efficiently confine and scatter light in the infrared range as the base of an all-optical displacement sensor. [...] Read more.
In this paper, we propose the design of an optical system based on two parallel suspended silicon nanowires that support a range of optical resonances that efficiently confine and scatter light in the infrared range as the base of an all-optical displacement sensor. The effects of the variation of the distance between the nanowires are analyzed. The simulation models are designed by COMSOL Multiphysics software, which is based on the finite element method. The diameter of the nanocylinders (d = 140 nm) was previously optimized to achieve resonances at the operating wavelengths (λ = 1064 nm and 1310 nm). The results pointed out that a detectable change in their resonant behavior and optical interaction was achieved. The proposed design aims to use a simple light source using a commercial diode laser and simplify the readout systems with a high sensitivity of 1.1 × 106 V/m2 and 1.14 × 106 V/m2 at 1064 nm and 1310 nm, respectively. The results may provide an opportunity to investigate alternative designs of displacement sensors from an all-optical approach and explore their potential use. Full article
(This article belongs to the Topic Advanced Nanomaterials for Sensing Applications)
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13 pages, 2852 KiB  
Article
Effect of Polymer Substrate on Adhesion of Electroless Plating in Irradiation-Based Direct Immobilization of Pd Nanoparticles Catalyst
by Naoto Uegaki, Satoshi Seino, Yuji Ohkubo and Takashi Nakagawa
Nanomaterials 2022, 12(22), 4106; https://doi.org/10.3390/nano12224106 - 21 Nov 2022
Cited by 1 | Viewed by 1277
Abstract
Pd nanoparticles were directly immobilized on acrylonitrile–butadiene–styrene copolymer (ABS), acrylonitrile–styrene copolymer (AS), polystyrene (PS), polyphenylene sulfide (PPS), poly(vinyl chloride) (PVC), polypropylene (PP), and polyethylene (PE) polymer substrates via chemical reactions induced by ionizing irradiation. X-ray photoelectron spectroscopy analysis revealed that the chemical state [...] Read more.
Pd nanoparticles were directly immobilized on acrylonitrile–butadiene–styrene copolymer (ABS), acrylonitrile–styrene copolymer (AS), polystyrene (PS), polyphenylene sulfide (PPS), poly(vinyl chloride) (PVC), polypropylene (PP), and polyethylene (PE) polymer substrates via chemical reactions induced by ionizing irradiation. X-ray photoelectron spectroscopy analysis revealed that the chemical state of the immobilized Pd nanoparticles depended on the polymer substrate type. Electroless plating was performed using the immobilized Pd nanoparticles as the catalyst, and Cu-plating films were deposited on all polymer substrates. The results of the tape-peeling test suggested that the chemical state of the immobilized Pd nanoparticles on the polymer substrates affected the plating adhesion strength. Notably, ABS with immobilized Pd particles exhibited a high adhesion strength beyond the practical level, even without prior chemical etching. It was presumed that the high adhesion strength was owing to the anchoring effect of the holes generated on the ABS surface by ionizing irradiation. Full article
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17 pages, 8391 KiB  
Article
Structural and Optical Properties of Graphene Quantum Dots−Polyvinyl Alcohol Composite Thin Film and Its Potential in Plasmonic Sensing of Carbaryl
by Nurul Illya Muhamad Fauzi, Yap Wing Fen, Faten Bashar Kamal Eddin and Wan Mohd Ebtisyam Mustaqim Mohd Daniyal
Nanomaterials 2022, 12(22), 4105; https://doi.org/10.3390/nano12224105 - 21 Nov 2022
Cited by 4 | Viewed by 2036
Abstract
In this study, graphene quantum dots (GQDs) and polyvinyl alcohol (PVA) composite was prepared and then coated on the surface of gold thin film via the spin coating technique. Subsequently, Fourier transform infrared spectroscopy (FT-IR), atomic force microscopy (AFM), and ultraviolet-visible spectroscopy (UV–Vis) [...] Read more.
In this study, graphene quantum dots (GQDs) and polyvinyl alcohol (PVA) composite was prepared and then coated on the surface of gold thin film via the spin coating technique. Subsequently, Fourier transform infrared spectroscopy (FT-IR), atomic force microscopy (AFM), and ultraviolet-visible spectroscopy (UV–Vis) were adopted to understand the structure, surface morphology, and optical properties of the prepared samples. The FT-IR spectral analysis revealed important bands, such as O–H stretching, C=O stretching, C-H stretching, and O=C=O stretching vibrations. The surface roughness of the GQDs-PVA composite thin film was found to be increased after exposure to carbaryl. On the other hand, the optical absorbance of the GQDs-PVA thin film was obtained and further analysis was conducted, revealing a band gap Eg value of 4.090 eV. The sensing potential of the thin film was analyzed using surface plasmon resonance (SPR) spectroscopy. The findings demonstrated that the developed sensor’s lowest detection limit for carbaryl was 0.001 ppb, which was lower than that previously reported, i.e., 0.007 ppb. Moreover, other sensing performance parameters, such as full width at half maximum, detection accuracy, and signal-to-noise ratio, were also investigated to evaluate the sensor’s efficiency. Full article
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9 pages, 5183 KiB  
Article
A Bioinspired Ag Nanoparticle/PPy Nanobowl/TiO2 Micropyramid SERS Substrate
by Xin Li, Florian Ion Tiberiu Petrescu, Qupei Danzeng, Haiyan Zhu, Ying Li and Gang Shi
Nanomaterials 2022, 12(22), 4104; https://doi.org/10.3390/nano12224104 - 21 Nov 2022
Cited by 1 | Viewed by 1148
Abstract
In this paper, the micropyramid structure was transferred to the TiO2 substrate by soft imprinting. Then, the PPy nanobowls were assembled onto the surface of the TiO2 micropyramids through the induction of the PS template. Finally, a layer of Ag nanoparticles [...] Read more.
In this paper, the micropyramid structure was transferred to the TiO2 substrate by soft imprinting. Then, the PPy nanobowls were assembled onto the surface of the TiO2 micropyramids through the induction of the PS template. Finally, a layer of Ag nanoparticles was deposited on the surface of PPy nanobowls to form a novel Ag nanoparticle/PPy nanobowl/TiO2 micropyramid SERS substrate. Its structure is similar to the bioinspired compound eyes. This substrate exhibited excellent antireflection, ultra-sensitivity, excellent uniformity, and recyclability. The concentration of R6G molecules can be detected as low as 10−9 mol/L, and the Raman enhancement factor can reach 3.4 × 105. In addition, the excellent catalytic degradation performance of the substrate ensures recyclability. This work proves that the micropyramid structure can be applied to other SERS materials besides silicon by the above methods, which broadens the selection range of composite SERS materials. Full article
(This article belongs to the Special Issue Nanostructured Materials for Energy Applications)
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12 pages, 4006 KiB  
Article
Modification of Frictional Properties of Hydrogel Surface via Laser Ablated Topographical Micro-Textures
by Zhuangzhuang Zhou, Yihang Chu, Zhishan Hou, Xiaopeng Zhou and Yu Cao
Nanomaterials 2022, 12(22), 4103; https://doi.org/10.3390/nano12224103 - 21 Nov 2022
Cited by 2 | Viewed by 1271
Abstract
Hydrogels and biological cartilage tissues are highly similar in structure and composition due to their unique characteristics such as high-water content and low friction coefficients. The introduction of hydrogel cartilage can effectively reduce the friction coefficient and wear coefficient of the original bone [...] Read more.
Hydrogels and biological cartilage tissues are highly similar in structure and composition due to their unique characteristics such as high-water content and low friction coefficients. The introduction of hydrogel cartilage can effectively reduce the friction coefficient and wear coefficient of the original bone joint and the implanted metal bone joint (generally titanium alloy or stainless steel), which is considered as a perfect replacement material for artificial articular cartilage. How to accurately regulate the local tribological characteristics of hydrogel artificial cartilage according to patient weight and bone shape is one of the important challenges in the current clinical application field of medical hydrogels. In this study, the mechanism by which micro-pits improve the surface friction properties was studied. Ultraviolet lasers were used to efficiently construct micro-pits with different shapes on a polyvinyl alcohol hydrogel in one step. It was shown that by using such a maskless laser processing, the performance of each part of the artificial cartilage can be customized flexibly and effectively. We envision that the approach demonstrated in this article will provide an important idea for the development of a high-performance, continuous and accurate method for controlling surface friction properties of artificial cartilage. Full article
(This article belongs to the Special Issue Surface Fabrication and Modification of Nanomaterials)
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17 pages, 4466 KiB  
Article
Time-Dependent Flow of Water-Based CoFe2O4-Mn-ZnFe2O4 Nanoparticles over a Shrinking Sheet with Mass Transfer Effect in Porous Media
by Iskandar Waini, Umair Khan, Aurang Zaib, Anuar Ishak, Ioan Pop and Nevzat Akkurt
Nanomaterials 2022, 12(22), 4102; https://doi.org/10.3390/nano12224102 - 21 Nov 2022
Cited by 3 | Viewed by 983
Abstract
The use of hybrid nanoparticles to increase heat transfer is a favorable area of research, and therefore, numerous scientists, researchers, and scholars have expressed their appreciation for and interest in this field. Determining the dynamic role of nanofluids in the cooling of microscopic [...] Read more.
The use of hybrid nanoparticles to increase heat transfer is a favorable area of research, and therefore, numerous scientists, researchers, and scholars have expressed their appreciation for and interest in this field. Determining the dynamic role of nanofluids in the cooling of microscopic electronic gadgets, such as microchips and related devices, is also one of the fundamental tasks. With such interesting and useful applications of hybrid nanofluids in mind, the main objective is to deal with the analysis of the unsteady flow towards a shrinking sheet in a water-based hybrid ferrite nanoparticle in porous media, with heat sink/source effects. Moreover, the impact of these parameters on heat and mass transfers is also reported. Numerical results are obtained using MATLAB software. Non-unique solutions are determined for a certain shrinking strength, in addition to the unsteadiness parameter. The mass transfer and friction factor increase for the first solution due to the hybrid nanoparticles, but the heat transfer rate shows the opposite effect. Full article
(This article belongs to the Special Issue Thermal Properties of Nanomaterials: Fundamentals and Applications)
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25 pages, 4887 KiB  
Article
Phase and Structural Thermal Evolution of Bi–Si–O Catalysts Obtained via Laser Ablation
by Anastasiia V. Shabalina, Alexandra G. Golubovskaya, Elena D. Fakhrutdinova, Sergei A. Kulinich, Olga V. Vodyankina and Valery A. Svetlichnyi
Nanomaterials 2022, 12(22), 4101; https://doi.org/10.3390/nano12224101 - 21 Nov 2022
Cited by 8 | Viewed by 1402
Abstract
Laser methods are successfully used to prepare complex functional nanomaterials, especially for biomedicine, optoelectronics, and heterogeneous catalysis. In this paper, we present complex oxide and composite nanomaterials based on Bi and Si produced using laser ablation in liquid followed by subsequent powder annealing. [...] Read more.
Laser methods are successfully used to prepare complex functional nanomaterials, especially for biomedicine, optoelectronics, and heterogeneous catalysis. In this paper, we present complex oxide and composite nanomaterials based on Bi and Si produced using laser ablation in liquid followed by subsequent powder annealing. Two synthesis approaches were used, with and without laser post-treatment of mixed (in an atomic ratio of 2:1) laser-generated Bi and Si colloids. A range of methods were used to characterize the samples: UV-Vis diffusion reflection, IR and Raman spectroscopy, synchronous thermal analysis, X-ray diffraction, transmission electron microscopy, as well as specific surface-area evaluation. We also followed the dynamics of phase transformations, as well as composition, structure and morphology of annealed powders up to 800 °C. When heated, the non-irradiated series of samples proceeded from metallic bismuth, through β-Bi2O3, and resulted in bismuth silicates of various stoichiometries. At the same time, in their laser-irradiated counterparts, the formation of silicates proceeded immediately from the amorphous Bi2SiO5 phase formed after laser treatment of mixed Bi and Si colloids. Finally, we show their ability to decompose persistent organic molecules of Rhodamine B and phenol under irradiation with a soft UV (375 nm) source. Full article
(This article belongs to the Special Issue Laser Synthesis and Processing of Nanostructured Materials)
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14 pages, 2831 KiB  
Article
Novel PEPPSI-Type NHC Pd(II) Metallosurfactants on the Base of 1H-Imidazole-4,5-dicarboxylic Acid: Synthesis and Catalysis in Water–Organic Media
by Vladimir Burilov, Dmitriy Radaev, Elza Sultanova, Diana Mironova, Daria Duglav, Vladimir Evtugyn, Svetlana Solovieva and Igor Antipin
Nanomaterials 2022, 12(22), 4100; https://doi.org/10.3390/nano12224100 - 21 Nov 2022
Cited by 4 | Viewed by 1229
Abstract
Carrying out organic reactions in water has attracted much attention. Catalytic reactions in water with metallosurfactants, which have both a metallocenter and the surface activity necessary for solubilizing hydrophobic reagents, are of great demand. Herein we proposed new approach to the synthesis of [...] Read more.
Carrying out organic reactions in water has attracted much attention. Catalytic reactions in water with metallosurfactants, which have both a metallocenter and the surface activity necessary for solubilizing hydrophobic reagents, are of great demand. Herein we proposed new approach to the synthesis of NHC PEPPSI metallosurfactants based on the sequential functionalization of imidazole 4,5-dicarboxylic acid with hydrophilic oligoethylene glycol and lipophilic alkyl fragments. Complexes of different lipophilicity were obtained, and their catalytic activity was studied in model reduction and Suzuki–Miyaura reactions. A comparison was made with the commercial PEPPSI-type catalytic systems designed by Organ. It was found that the reduction reaction in an aqueous solution of the metallosurfactant with the tetradecyl lipophilic fragment was three times more active than the commercially available PEPPSI complexes, which was associated with the formation of stable monodisperse aggregates detected by DLS and TEM. Full article
(This article belongs to the Special Issue Nanostructures Design for Catalyst: Latest Advances and Prospects)
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15 pages, 6284 KiB  
Article
Influence of Dopant Concentration and Annealing on Binary and Ternary Polymer Blends for Active Materials in OLEDs
by Maria Gioti, Despoina Tselekidou, Vasileios Foris, Vasileios Kyriazopoulos, Kyparisis Papadopoulos, Spyros Kassavetis and Stergios Logothetidis
Nanomaterials 2022, 12(22), 4099; https://doi.org/10.3390/nano12224099 - 21 Nov 2022
Cited by 3 | Viewed by 1312
Abstract
Obtaining white light from organic LEDs is a considerable challenge and, to realize white light emission, many studies have been conducted, primarily addressing two- or three-color blend systems as a promising strategy. In this work, pristine films, grown by spin coating, consisting of [...] Read more.
Obtaining white light from organic LEDs is a considerable challenge and, to realize white light emission, many studies have been conducted, primarily addressing two- or three-color blend systems as a promising strategy. In this work, pristine films, grown by spin coating, consisting of commercial blue Poly(9,9-di-n-octylfluorenyl-2,7-diyl) (PFO), green Poly(9,9-dioctylfluorene-alt-benzothiadiazole) (F8BT), and red spiro-copolymer (SPR) light-emitting materials, were studied as reference materials. Afterward, binary (SPR doped in host PFO) and ternary (SPR and F8BT doped in host PFO) thin films were successfully prepared with various ratios. The characterization of the as-grown and thermally-treated blend films was focused on their optical and photophysical properties. After, the fabrication of OLED devices on glass substrates was carried out for the evaluation of a blend’s composition and annealing in terms of the devices’ electrical characteristics and electro-emission properties in order to achieve white light emission. Their analysis provided insights into the energy transfer mechanisms between the constituent materials, which were correlated to host–guest interactions as well as to the structural changes originated by thermal treatment, leading to the crystallization of PFO. Finally, the OLEDs based on ternary blends approach the white light emission with (x, y) of (0.272, 0.346). These fabricated devices also exhibit turn-on voltages as low as 3 V, accompanied by remarkable luminance values above 3000 cd/m2. Full article
(This article belongs to the Section Nanophotonics Materials and Devices)
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20 pages, 3981 KiB  
Article
Dynamic Instability of Functionally Graded Graphene Platelet-Reinforced Porous Beams on an Elastic Foundation in a Thermal Environment
by Jing Zhang, Ying Lv and Lianhe Li
Nanomaterials 2022, 12(22), 4098; https://doi.org/10.3390/nano12224098 - 21 Nov 2022
Cited by 4 | Viewed by 1194
Abstract
Under thermal environment and axial forces, the dynamic instability of functionally graded graphene platelet (GPLs)-reinforced porous beams on an elastic foundation is investigated. Three modes of porosity distributions and GPL patterns are considered. The governing equations are given by the Hamilton principle. On [...] Read more.
Under thermal environment and axial forces, the dynamic instability of functionally graded graphene platelet (GPLs)-reinforced porous beams on an elastic foundation is investigated. Three modes of porosity distributions and GPL patterns are considered. The governing equations are given by the Hamilton principle. On the basis of the differential quadrature method (DQM), the governing equations are changed into Mathieu–Hill equations, and the main unstable regions of the porous composite beams are studied by the Bolotin method. Thermal buckling and thermo-mechanical vibration problems are also studied. The effects of porosity coefficients and GPL weight fraction, dispersion pattern, initial thermal loading, slenderness ratio, geometry and size, boundary conditions, and foundation stiffness are discussed. The conclusions show that an elastic foundation has an obvious enhancement effect on thermal buckling, free vibration, and dynamic instability, which improves the stiffness of the beam. Full article
(This article belongs to the Special Issue Advances of Nanoscale Fluid Mechanics)
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16 pages, 3141 KiB  
Article
Stable Configurations of DOXH Interacting with Graphene: Heuristic Algorithm Approach Using NSGA-II and U-NSGA-III
by Kanes Sumetpipat and Duangkamon Baowan
Nanomaterials 2022, 12(22), 4097; https://doi.org/10.3390/nano12224097 - 21 Nov 2022
Viewed by 1223
Abstract
Nanoparticles in drug delivery have been widely studied and have become a potential technique for cancer treatment. Doxorubicin (DOX) and carbon graphene are candidates as a drug and a nanocarrier, respectively, and they can be modified or decorated by other molecular functions to [...] Read more.
Nanoparticles in drug delivery have been widely studied and have become a potential technique for cancer treatment. Doxorubicin (DOX) and carbon graphene are candidates as a drug and a nanocarrier, respectively, and they can be modified or decorated by other molecular functions to obtain more controllable and stable systems. A number of researchers focus on investigating the energy, atomic distance, bond length, system formation and their properties using density function theory and molecular dynamic simulation. In this study, we propose metaheuristic optimization algorithms, NSGA-II and U-NSGA-III, to find the interaction energy between DOXH molecules and pristine graphene in three systems: (i) interacting between two DOXHs, (ii) one DOXH interacting with graphene and (iii) two DOXHs interacting with graphene. The result shows that the position of the carbon ring plane of DOXH is noticeably a key factor of stability. In the first system, there are three possible, stable configurations where their carbon ring planes are oppositely parallel, overlapping and perpendicular. In the second system, the most stable configuration is the parallel form between the DOXH carbon ring plane and graphene, and the spacing distance from the closest atom on the DOXH to the graphene is 2.57 Å. In the last system, two stable configurations are formed, where carbon ring planes from the two DOXHs lie either in the opposite direction or in the same direction and are parallel to the graphene sheet. All numerical results show good agreement with other studies. Full article
(This article belongs to the Section Theory and Simulation of Nanostructures)
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12 pages, 4763 KiB  
Article
Hyper-FET’s Phase-Transition-Materials Design Guidelines for Ultra-Low Power Applications at 3 nm Technology Node
by Hanggyo Jung, Jeesoo Chang, Changhyun Yoo, Jooyoung Oh, Sumin Choi, Juyeong Song and Jongwook Jeon
Nanomaterials 2022, 12(22), 4096; https://doi.org/10.3390/nano12224096 - 21 Nov 2022
Cited by 3 | Viewed by 1563
Abstract
In this work, a hybrid-phase transition field-effects-transistor (hyper-FET) integrated with phase-transition materials (PTM) and a multi-nanosheet FET (mNS-FET) at the 3 nm technology node were analyzed at the device and circuit level. Through this, a benchmark was performed for presenting device design guidelines [...] Read more.
In this work, a hybrid-phase transition field-effects-transistor (hyper-FET) integrated with phase-transition materials (PTM) and a multi-nanosheet FET (mNS-FET) at the 3 nm technology node were analyzed at the device and circuit level. Through this, a benchmark was performed for presenting device design guidelines and for using ultra-low-power applications. We present an optimization flow considering hyper-FET characteristics at the device and circuit level, and analyze hyper-FET performance according to the phase transition time (TT) and baseline-FET off-leakage current (IOFF) variations of the PTM. As a result of inverter ring oscillator (INV RO) circuit analysis, the optimized hyper-FET increases speed by +8.74% and reduces power consumption by −16.55%, with IOFF = 5 nA of baseline-FET and PTM TT = 50 ps compared to the conventional mNS-FET in the ultra-low-power region. As a result of SRAM circuit analysis, the read static noise margin is improved by 43.9%, and static power is reduced by 58.6% in the near-threshold voltage region when the PTM is connected to the pull-down transistor source terminal of 6T SRAM for high density. This is achieved at 41% read current penalty. Full article
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14 pages, 6054 KiB  
Article
Size-Dependent Superconducting Properties of In Nanowire Arrays
by Alexey A. Noyan, Yevgeniy A. Ovchenkov, Valery V. Ryazanov, Igor A. Golovchanskiy, Vasily S. Stolyarov, Eduard E. Levin and Kirill S. Napolskii
Nanomaterials 2022, 12(22), 4095; https://doi.org/10.3390/nano12224095 - 21 Nov 2022
Viewed by 1541
Abstract
Arrays of superconducting nanowires may be useful as elements of novel nanoelectronic devices. The superconducting properties of nanowires differ significantly from the properties of bulk structures. For instance, different vortex configurations of the magnetic field have previously been predicted for nanowires with different [...] Read more.
Arrays of superconducting nanowires may be useful as elements of novel nanoelectronic devices. The superconducting properties of nanowires differ significantly from the properties of bulk structures. For instance, different vortex configurations of the magnetic field have previously been predicted for nanowires with different diameters. In the present study, arrays of parallel superconducting In nanowires with the diameters of 45 nm, 200 nm, and 550 nm—the same order of magnitude as coherence length ξ—were fabricated by templated electrodeposition. Values of magnetic moment M of the samples were measured as a function of magnetic field H and temperature T in axial and transverse fields. M(H) curves for the arrays of nanowires with 45 nm and 200 nm diameters are reversible, whereas magnetization curves for the array of nanowires with 550 nm diameter have several feature points and show a significant difference between increasing and decreasing field branches. Critical fields increase with a decrease in diameter, and the thinnest nanowires exceed bulk critical fields by 20 times. The qualitative change indicates that magnetic field configurations are different in the nanowires with different diameters. Variation of M(H) slope in small fields, heat capacity, and the magnetic field penetration depth with the temperature were measured. Superconductivity in In nanowires is proven to exist above the bulk critical temperature. Full article
(This article belongs to the Special Issue Advanced Spintronic and Electronic Nanomaterials)
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11 pages, 2372 KiB  
Article
Flexible and Lightweight Carbon Nanotube Composite Filter for Particulate Matter Air Filtration
by Megha Chitranshi, Daniel Rui Chen, Peter Kosel, Marc Cahay and Mark Schulz
Nanomaterials 2022, 12(22), 4094; https://doi.org/10.3390/nano12224094 - 21 Nov 2022
Cited by 2 | Viewed by 1749
Abstract
Particulate Matter (PM) has become an important source of air pollution. We proposed a flexible and lightweight carbon nanotube (CNT) composite air filter for PM removal. The developed CNT filtering layers were fabricated using a floating catalyst chemical vapor deposition (FC-CVD) synthesis process [...] Read more.
Particulate Matter (PM) has become an important source of air pollution. We proposed a flexible and lightweight carbon nanotube (CNT) composite air filter for PM removal. The developed CNT filtering layers were fabricated using a floating catalyst chemical vapor deposition (FC-CVD) synthesis process and then combined with conventional filter fabrics to make a composite air filter. Filtration performance for CNT filtering layer alone and composited with other conventional filter fabrics for particles size 0.3 μm to 2.5 μm was investigated in this study. The CNT composite filter is highly hydrophobic, making it suitable for humid environments. The CNT composite filter with two layers of tissue CNT performed best and achieved a filtration efficiency over 90% with a modest pressure drop of ~290 Pa for a particle size of 2.5 μm. This CNT composite filter was tested over multiple cycles to ensure its reusability. The developed filter is very light weight and flexible and can be incorporated into textiles for wearable applications or used as a room filter. Full article
(This article belongs to the Special Issue Functional Carbon-Based Nanocomposite and Applications)
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12 pages, 3085 KiB  
Article
Ethanol Electrooxidation at 1–2 nm AuPd Nanoparticles
by Juliette W. Strasser and Richard M. Crooks
Nanomaterials 2022, 12(22), 4093; https://doi.org/10.3390/nano12224093 - 21 Nov 2022
Cited by 1 | Viewed by 1019
Abstract
We report a systematic study of the electrocatalytic properties and stability of a series of 1–2 nm Au, Pd, and AuPd alloy nanoparticles (NPs) for the ethanol oxidation reaction (EOR). Following EOR electrocatalysis, NP sizes and compositions were characterized using aberration-corrected scanning transmission [...] Read more.
We report a systematic study of the electrocatalytic properties and stability of a series of 1–2 nm Au, Pd, and AuPd alloy nanoparticles (NPs) for the ethanol oxidation reaction (EOR). Following EOR electrocatalysis, NP sizes and compositions were characterized using aberration-corrected scanning transmission electron microscopy (ac-STEM) and energy dispersive spectroscopy (EDS). Two main findings emerge from this study. First, alloyed AuPd NPs exhibit enhanced electrocatalytic EOR activity compared to either monometallic Au or Pd NPs. Specifically, NPs having a 3:1 ratio of Au:Pd exhibit an ~8-fold increase in peak current density compared to Pd NPs, with an onset potential shifted ~200 mV more to the negative compared to Au NPs. Second, the size and composition of AuPd alloy NPs do not (within experimental error) change following 1.0 or 2.0 h chronoamperometry experiments, while monometallic Au NPs increase in size from 2 to 5 nm under the same conditions. Notably, this report demonstrates the importance of post-catalytic ac-STEM/EDS characterization for fully evaluating NP activity and stability, especially for 1–2 nm NPs that may change in size or structure during electrocatalysis. Full article
(This article belongs to the Special Issue Nanomaterials and Nanotechnology for Electrocatalytic Applications)
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12 pages, 2000 KiB  
Article
Nanoscale Printing of Indium-Tin-Oxide by Femtosecond Laser Pulses
by Jingwen Hu, Zhen-Ze Li, Yang-Yang Zhao, Yi-Shi Xu, Lin Wang, Molong Han, Lachlan Hyde, Soon Hock Ng, Lei Wang and Saulius Juodkazis
Nanomaterials 2022, 12(22), 4092; https://doi.org/10.3390/nano12224092 - 21 Nov 2022
Cited by 1 | Viewed by 1583
Abstract
For constructing optical and electrical micro-devices, the deposition/printing of materials with sub-1 μm precision and size (cross-section) is required. Crystalline c-ITO (indium tin oxide) nanostructures were patterned on glass with sufficient precision to form 20–50 nm gaps between individual disks or lines [...] Read more.
For constructing optical and electrical micro-devices, the deposition/printing of materials with sub-1 μm precision and size (cross-section) is required. Crystalline c-ITO (indium tin oxide) nanostructures were patterned on glass with sufficient precision to form 20–50 nm gaps between individual disks or lines of ∼250 nm diameter or width. The absorbed energy density [J/cm3] followed a second-order dependence on pulse energy. This facilitated high-resolution and precise nanoscale laser-writing at a laser wavelength of 515 nm. Patterns for optical elements such as circular gratings and micro-disks were laser-printed using ITO as a resist. Unexposed amorphous a-ITO was chemically removed in aqueous 1% vol. HF solution. This use of a-ITO as a solid resist holds promise for metamaterial and micro-optical applications. Full article
(This article belongs to the Section Nanofabrication and Nanomanufacturing)
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12 pages, 4121 KiB  
Article
Lead-Free Bi0.5Na0.5TiO3 Ferroelectric Nanomaterials for Pyro-Catalytic Dye Pollutant Removal under Cold-Hot Alternation
by Zheng Wu, Siqi Wu, Siqi Hong, Xiaoyu Shi, Di Guo, Yan Zhang, Xiaoli Xu, Zhi Chen and Yanmin Jia
Nanomaterials 2022, 12(22), 4091; https://doi.org/10.3390/nano12224091 - 21 Nov 2022
Cited by 9 | Viewed by 1625
Abstract
In this work, explicitly pyro-catalytic performance is observed in sol-gel-synthesized ferroelectric Bi0.5Na0.5TiO3 lead-free nanomaterials, and its application for dye wastewater purification is also actualized under temperature fluctuations varying from 23 °C to 63 °C. The decomposition ratios of [...] Read more.
In this work, explicitly pyro-catalytic performance is observed in sol-gel-synthesized ferroelectric Bi0.5Na0.5TiO3 lead-free nanomaterials, and its application for dye wastewater purification is also actualized under temperature fluctuations varying from 23 °C to 63 °C. The decomposition ratios of the pyro-catalytic Bi0.5Na0.5TiO3 nanomaterials on Rhodamine B, methyl blue and methyl orange can reach 96.75%, 98.35% and 19.97%, respectively. In the pyro-catalytic process, the probed active species such as hydroxyl radicals, superoxide radicals and holes play an extremely important role in decomposing dye molecules. The ferroelectric Bi0.5Na0.5TiO3 lead-free nanomaterials will have an excellent prospect for dye wastewater purification due to its explicit pyro-catalysis. Full article
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11 pages, 2444 KiB  
Article
Analysis of Formation Mechanisms of Sugar-Derived Dense Carbons via Hydrogel Carbonization Method
by Liting Chen, Zheqiong Fan, Weiguo Mao, Cuiying Dai, Daming Chen and Xinghong Zhang
Nanomaterials 2022, 12(22), 4090; https://doi.org/10.3390/nano12224090 - 21 Nov 2022
Cited by 2 | Viewed by 1663
Abstract
Four kinds of sugar (glucose, fructose, sucrose, and maltose) were selected as carbon precursors, and corresponding dense carbon products were prepared using a novel hydrogel carbonization method. The carbonization processes of sugar–polyacrylamide (sugar–PAM) hydrogels were studied in detail. The molecular structures in the [...] Read more.
Four kinds of sugar (glucose, fructose, sucrose, and maltose) were selected as carbon precursors, and corresponding dense carbon products were prepared using a novel hydrogel carbonization method. The carbonization processes of sugar–polyacrylamide (sugar–PAM) hydrogels were studied in detail. The molecular structures in the raw materials were analyzed by proton nuclear magnetic resonance spectroscopy (1H NMR). Samples prepared at different temperatures were characterized by thermogravimetry analysis (TGA) and Fourier-transform infrared (FTIR) spectroscopy. The morphology and microstructure of sugar-derived carbons were confirmed by field-emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD). The results indicated that the sugar solution was surrounded by PAM with a three-dimensional network structure and formed hydrogels in the initial stage. The sugar solution was considered to be separated into nanocapsules. In each nanocapsule, sugar molecules could be limited within the hydrogel via walls formed by PAM chains. The hydroxyl group in the sugar molecules connected with PAM by the hydrogen bond and intermolecular force, which can strengthen the entire hydrogel system. The self-generated pressure of hydrogel constrains the foam of sugar during the heat treatment. Finally, dense carbon materials with low graphitization instead of porous structure were prepared at 1200 °C. Full article
(This article belongs to the Special Issue Advanced Carbon Chemistry and Its Applications)
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12 pages, 1024 KiB  
Article
Burden of Disease (BoD) Assessment to Estimate Risk Factors Impact in a Real Nanomanufacturing Scenario
by Antti Joonas Koivisto, Marko Altin, Irini Furxhi, Maxime Eliat, Sara Trabucco, Magda Blosi, Jesús Lopez de Ipiña, Franco Belosi and Anna Costa
Nanomaterials 2022, 12(22), 4089; https://doi.org/10.3390/nano12224089 - 21 Nov 2022
Viewed by 1737
Abstract
An industrial nanocoating process air emissions impact on public health was quantified by using the burden of disease (BoD) concept. The health loss was calculated in Disability Adjusted Life Years (DALYs), which is an absolute metric that enables comparisons of the health impacts [...] Read more.
An industrial nanocoating process air emissions impact on public health was quantified by using the burden of disease (BoD) concept. The health loss was calculated in Disability Adjusted Life Years (DALYs), which is an absolute metric that enables comparisons of the health impacts of different causes. Here, the health loss was compared with generally accepted risk levels for air pollution. Exposure response functions were not available for Ag nanoform. The health loss for TiO2 nanoform emissions were 0.0006 DALYs per 100,000 persons per year. Moreover, the exposure risk characterization was performed by comparing the ground level air concentrations with framework values. The exposure levels were ca. 3 and 18 times lower than the derived limit values of 0.1 μg-TiO2/m3 and 0.01 μg-Ag/m3 for the general population. The accumulations of TiO2 and Ag nanoforms on the soil top layer were estimated to be up to 85 μg-TiO2/kg and 1.4 μg-Ag/kg which was considered low as compared to measured elemental TiO2 and Ag concentrations. This assessment reveals that the spray coating process air emissions are adequately controlled. This study demonstrated how the BoD concept can be applied to quantify health impacts of nanoform outdoor air emissions from an industrial site. Full article
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12 pages, 3591 KiB  
Article
Ultrafast Dynamics of Demagnetization in FeMn/MnGa Bilayer Nanofilm Structures via Phonon Transport
by Tianran Jiang, Xupeng Zhao, Zhifeng Chen, Yongyong You, Tianshu Lai and Jianhua Zhao
Nanomaterials 2022, 12(22), 4088; https://doi.org/10.3390/nano12224088 - 20 Nov 2022
Cited by 3 | Viewed by 1281
Abstract
Superdiffusive spin transport has been proposed as a new mechanism of ultrafast demagnetization in layered magnetic nanostructures and demonstrated experimentally. However, it is unknown if it is possible for phonon transport to occur and manipulate ultrafast demagnetization. Here, we explore the ultrafast dynamics [...] Read more.
Superdiffusive spin transport has been proposed as a new mechanism of ultrafast demagnetization in layered magnetic nanostructures and demonstrated experimentally. However, it is unknown if it is possible for phonon transport to occur and manipulate ultrafast demagnetization. Here, we explore the ultrafast dynamics of demagnetization of an antiferromagnet/ferromagnet bilayer nanostructure, of a FeMn/MnGa bilayer film prepared by molecular beam epitaxy. Ultrafast dynamics of a two-step demagnetization were observed through the time-resolved magneto-optical Kerr effect. The first-step fast component of the two-step demagnetization occurred within ~200 fs, while the second-step slow component emerged in a few tens of picoseconds. For a single MnGa film, only the ultrafast dynamics of the first-step fast demagnetization were observed, revealing that the second-step slow demagnetization originates from interlayer phonon transport. A four-temperature model considering phonon transport was developed and used to effectively reproduce the observed ultrafast dynamics of two-step demagnetization. Our results reveal the effect of phonon transport on demagnetization for the first time and open up a new route to manipulate ultrafast demagnetization in layered magnetic structures. Full article
(This article belongs to the Section Nanophotonics Materials and Devices)
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12 pages, 3447 KiB  
Article
Improvement of Aerosol Filtering Performance of PLLA/PAN Composite Fiber with Gradient Structure
by Ping Zhu, Wang Sun and Yunchun Liu
Nanomaterials 2022, 12(22), 4087; https://doi.org/10.3390/nano12224087 - 20 Nov 2022
Cited by 3 | Viewed by 1246
Abstract
Since commercial non-woven air filtering materials have unstable filtering efficiency and poor moisture permeability for the abundant condensed aerosol particles in the highly humid atmospheric environment, the PLLA/PAN composite fiber material with a hydrophobic and hydrophilic gradient structure is designed and prepared by [...] Read more.
Since commercial non-woven air filtering materials have unstable filtering efficiency and poor moisture permeability for the abundant condensed aerosol particles in the highly humid atmospheric environment, the PLLA/PAN composite fiber material with a hydrophobic and hydrophilic gradient structure is designed and prepared by using electrode sputtering electro spinning technology. By characterizing and testing the filtrating effect of SEM, XRD, FTIR, wettability, mechanical property, N2 adsorption isotherm, and BET surface area, NaCl aerosol of PLLA fiber, PAN fiber, and PLLA/PAN composite fiber membranes, the study found that the electrode sputtering electrospinning is fine, the fiber mesh is dense, and fiber distribution is uniform when the diameter of the PAN fiber is 140–300 nm, and the PLLA fiber is 700–850 nm. In this case, PLLA/PAN composite fiber materials gather the hydrophobicity of PLLA fiber and the hydrophilicity of PAN fiber; its electrostatic effect is stable, its physical capturing performance is excellent, it can realize the step filtration of gas-solid liquid multiphase flow to avoid the rapid increase of air resistance in a high-humidity environment, and the filtrating efficiency η of NaCl aerosol particles with 0.3 μm reaches 99.98%, and the quality factor QF 0.0968 Pa−1. The manufacturing of PLLA/PAN composite fiber material provides a new method for designing and developing high-performance air filtration materials and a new technical means for the large-scale production of high-performance, high-stability, and low-cost polylactic acid nanofiber composites. Full article
(This article belongs to the Special Issue Nanofiltration Membranes)
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14 pages, 3778 KiB  
Article
Rapid and Effective Way to Synthesize Highly Crystalline Nanosized SAPO-34 Particles
by Irina Shamanaeva, Svetlana Strelova, Marina Solovyeva and Aleksandra Grekova
Nanomaterials 2022, 12(22), 4086; https://doi.org/10.3390/nano12224086 - 20 Nov 2022
Cited by 2 | Viewed by 1510
Abstract
SAPO-34 nanocrystals with sizes of 50–150 nm were obtained via steam-assisted crystallization (SAC) for 5 h at 200 °C from two types of aluminum precursors—aluminum isopropoxide and boehmite. A reaction mixture composition with a small amount of organic template tetraehylammonium hydroxide (TEAOH) was [...] Read more.
SAPO-34 nanocrystals with sizes of 50–150 nm were obtained via steam-assisted crystallization (SAC) for 5 h at 200 °C from two types of aluminum precursors—aluminum isopropoxide and boehmite. A reaction mixture composition with a small amount of organic template tetraehylammonium hydroxide (TEAOH) was used with the molar ratio TEAOH/Al2O3 = 1/1. The alumina precursor type and duration of the SAC (5 and 24 h) on the crystal size, texture, and acid properties were investigated. The SAPO-34 nanocrystals that we obtained possess a large micropore volume of 0.22–0.24 cm3/g and a specific surface area of 651–695 m2/g. When the crystallization was prolonged for up to 24 h, a SAPO-18 structure appeared, but the micropore and mesopore volumes changed insignificantly. Using boehmite as the aluminum precursor led to higher mesoporosity of the material but a little bit lower acidity when compared with the samples prepared from aluminum isopropoxide. In addition, the method proposed was used for preparing a SAPO-34-coated aluminum adsorber heat exchanger. Thus, the synthesis method proposed is affordable and effective to prepare SAPO-34 highly crystalline nanoparticles, with no need for post-synthetic procedures as the mother liquor separation from nanocrystals. Full article
(This article belongs to the Section Inorganic Materials and Metal-Organic Frameworks)
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17 pages, 4515 KiB  
Article
Cascade Förster Resonance Energy Transfer Studies for Enhancement of Light Harvesting on Dye-Sensitized Solar Cells
by Mulugeta Tesema Efa, Jheng-Chang Huang and Toyoko Imae
Nanomaterials 2022, 12(22), 4085; https://doi.org/10.3390/nano12224085 - 20 Nov 2022
Cited by 2 | Viewed by 1288
Abstract
This work reports cascade Förster resonance energy transfer (FRET)-based n-type (ZnO) and p-type (NiO) dye-sensitized solar cells (DSSCs), discussing approaches to enhance their overall performance. Although DSSCs suffer from poorer performance than other solar cells, the use of composites with carbon dot (Cdot) [...] Read more.
This work reports cascade Förster resonance energy transfer (FRET)-based n-type (ZnO) and p-type (NiO) dye-sensitized solar cells (DSSCs), discussing approaches to enhance their overall performance. Although DSSCs suffer from poorer performance than other solar cells, the use of composites with carbon dot (Cdot) can enhance the power conversion efficiency (PCE) of DSSCs. However, further improvements are demanded through molecular design to stimulate DSSCs. Here, a photosensitized system based on a cascade FRET was induced alongside the conventional photosensitizer dye (N719). To N719 in a DSSC is transferred the energy cascaded through donor fluorescence materials (pyrene, 3-acetyl-7-N,N-diethyl-coumarin or coumarin and acridine orange), and this process enhances the light-harvesting properties of the sensitizers in the DSSC across a broad region of the solar spectrum. PCE values of 10.7 and 11.3% were achieved for ZnO/Cdot and NiO/Cdot DSSCs, respectively. These high PCE values result from the energy transfer among multi-photosensitizers (cascade FRET fluorophores, N719, and Cdot). Moreover, Cdot can play a role in intensifying the adsorption of dyes and discouraging charge recombination on the semiconductor. The present results raise expectations that a significant improvement in photovoltaic performance can be attained of DSSCs exploiting the cascade FRET photonics phenomenon. Full article
(This article belongs to the Special Issue Quantum Materials for Photonic Devices)
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16 pages, 2769 KiB  
Article
Convective Heat Transfer in Magneto-Hydrodynamic Carreau Fluid with Temperature Dependent Viscosity and Thermal Conductivity
by Syed Amir Ghazi Ali Shah, Ali Hassan, Najah Alsubaie, Abdullah Alhushaybari, Fahad M. Alharbi, Ahmed M. Galal, Diana-Petronela Burduhos-Nergis and Costica Bejinariu
Nanomaterials 2022, 12(22), 4084; https://doi.org/10.3390/nano12224084 - 20 Nov 2022
Cited by 3 | Viewed by 1324
Abstract
This study is aimed to explore the magneto-hydrodynamic Carreau fluid flow over a stretching/shrinking surface with a convectively heated boundary. Temperature-dependent variable thermophysical properties are utilized to formulate the problem. The flow governing equations are obtained with boundary layer approximation and constitutive relation [...] Read more.
This study is aimed to explore the magneto-hydrodynamic Carreau fluid flow over a stretching/shrinking surface with a convectively heated boundary. Temperature-dependent variable thermophysical properties are utilized to formulate the problem. The flow governing equations are obtained with boundary layer approximation and constitutive relation of the Carreau fluid. The shooting method is utilized to obtain graphical and numeric outcomes. Additionally, initial guesses are generated with the help of Newton’s method. The effect of Weissenberg number, Magnetization, stretching ratio, Prandtl number, suction/blowing parameter, and Lewis number is obtained on velocity, temperature and species continuity profile and analyzed. Shear stress rates and Nusselt number outcomes under body forces influences are present in tabulated data and discussed. It is observed that in absence of magnetization force, B = 0 and strong mass suction 5S7.5 effect high rates of Nusselt number is obtained. It is concluded that under the influence of power law index and non-linearity parameter maximum heat transfer and reduced shear stress rates are obtained. Full article
(This article belongs to the Special Issue Advances of Nanoscale Fluid Mechanics)
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11 pages, 4956 KiB  
Article
CoSn3 Intermetallic Nanoparticles for Electronic Packaging
by Jintao Wang, Ziwen Lv, Luobin Zhang, Fangcheng Duan, Weiwei Zhang and Hongtao Chen
Nanomaterials 2022, 12(22), 4083; https://doi.org/10.3390/nano12224083 - 20 Nov 2022
Cited by 4 | Viewed by 1188
Abstract
At present, composite solder pastes are getting a lot of attention, especially composite Sn based solders reinforced by nanoparticles. Indeed, CoSn3 is a strong nucleating agent of Sn crystal, which has potential application value in the field of electronic packaging. However, there [...] Read more.
At present, composite solder pastes are getting a lot of attention, especially composite Sn based solders reinforced by nanoparticles. Indeed, CoSn3 is a strong nucleating agent of Sn crystal, which has potential application value in the field of electronic packaging. However, there is no reliable synthetic path for CoSn3 nanoparticles at present. In this article, a chemical synthesis method for CoSn3 nanoparticles is developed. Here, CoCl2 and SnCl2 are reduced by NaHB4 in triethylene glycol (TEG), dispersed by ultrasonics, and heated to 350 °C in a tube furnace for growth. The CoSn3 nanoparticles with a diameter of about 150 nm are obtained by heating at 350 °C for 10 min. The CoSn3 nanoparticles undergo a step reaction in the process of synthesis and go through different stages of merging and annexation during their growth. The crystal growth behavior and the process of orientation change during the nucleation and growth of CoSn3 nanoparticles are studied, especially the two growth mechanisms, namely OU (orientation unified) and OA (orientation attached). By mixing CoSn3 nanoparticles with SAC305, we obtain a kind of strengthened composite soldering paste. There are obvious six-fold cyclic twins in the joints made by this soldering paste. Full article
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13 pages, 531 KiB  
Article
Totally Spin-Polarized Currents in an Interferometer with Spin–Orbit Coupling and the Absence of Magnetic Field Effects
by Victor Lopes, Guillermo Chiappe, Laercio C. Ribeiro and Enrique V. Anda
Nanomaterials 2022, 12(22), 4082; https://doi.org/10.3390/nano12224082 - 20 Nov 2022
Viewed by 1299
Abstract
The paper studies the electronic current in a one-dimensional lead under the effect of spin–orbit coupling and its injection into a metallic conductor through two contacts, forming a closed loop. When an external potential is applied, the time reversal symmetry is broken and [...] Read more.
The paper studies the electronic current in a one-dimensional lead under the effect of spin–orbit coupling and its injection into a metallic conductor through two contacts, forming a closed loop. When an external potential is applied, the time reversal symmetry is broken and the wave vector k of the circulating electrons that contribute to the current is spin-dependent. As the wave function phase depends upon the vector k, the closed path in the circuit produces spin-dependent current interference. This creates a physical scenario in which a spin-polarized current emerges, even in the absence of external magnetic fields or magnetic materials. It is possible to find points in the system’s parameter space and, depending upon its geometry, the value of the Fermi energy and the spin–orbit intensities, for which the electronic states participating in the current have only one spin, creating a high and totally spin-polarized conductance. For a potential of a few tens of meV, it is possible to obtain a spin-polarized current of the order of μA. The properties of the obtained electronic current qualify the proposed device as a potentially important tool for spintronics applications. Full article
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11 pages, 4010 KiB  
Article
Fast Responsive, Reversible Colorimetric Nanoparticle-Hydrogel Complexes for pH Monitoring
by Yeonjin Kim, Taeha Lee, Minsu Kim, Soojin Park, Jiashu Hu, Kyungwon Lee, Yoochan Hong, Insu Park and Gyudo Lee
Nanomaterials 2022, 12(22), 4081; https://doi.org/10.3390/nano12224081 - 20 Nov 2022
Cited by 3 | Viewed by 1994
Abstract
Hydrogels containing redox-sensitive colorimetric nanoparticles (NPs) have been used to sense ambient pH in many fields owing to their simple and fast visualization capabilities. However, real-time pH monitoring still has limitations due to its poor response rate and irreversibility. Herein, we developed a [...] Read more.
Hydrogels containing redox-sensitive colorimetric nanoparticles (NPs) have been used to sense ambient pH in many fields owing to their simple and fast visualization capabilities. However, real-time pH monitoring still has limitations due to its poor response rate and irreversibility. Herein, we developed a fast responsive colorimetric hydrogel called ferrocene adsorption colorimetric hydrogel (FACH). Ferrocene, an organometallic compound, plays a vital role as an electron transfer mediator (i.e., redox catalyst) within the hydrogel network. FACH shows fast color change performance with high reactivity and penetrability to ambient pH changes. In detail, FACH shows distinct color change within 2 min under various pH conditions from four to eight, with good reliability. The speed for color change of FACH is approximately six times faster than that of previously developed colorimetric hydrogels, suggesting the fastest hydrogel-based colorimetric pH sensor. Furthermore, FACH shows reversibility and repeatability of the redox process, indicating scalable utility as a sustainable pH monitoring platform. Full article
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18 pages, 1742 KiB  
Review
A Structural Analysis of Proteinaceous Nanotube Cavities and Their Applications in Nanotechnology
by Fabian Heide and Jörg Stetefeld
Nanomaterials 2022, 12(22), 4080; https://doi.org/10.3390/nano12224080 - 20 Nov 2022
Cited by 1 | Viewed by 1612
Abstract
Protein nanotubes offer unique properties to the materials science field that allow them to fulfill various functions in drug delivery, biosensors and energy storage. Protein nanotubes are chemically diverse, modular, biodegradable and nontoxic. Furthermore, although the initial design or repurposing of such nanotubes [...] Read more.
Protein nanotubes offer unique properties to the materials science field that allow them to fulfill various functions in drug delivery, biosensors and energy storage. Protein nanotubes are chemically diverse, modular, biodegradable and nontoxic. Furthermore, although the initial design or repurposing of such nanotubes is highly complex, the field has matured to understand underlying chemical and physical properties to a point where applications are successfully being developed. An important feature of a nanotube is its ability to bind ligands via its internal cavities. As ligands of interest vary in size, shape and chemical properties, cavities have to be able to accommodate very specific features. As such, understanding cavities on a structural level is essential for their effective application. The objective of this review is to present the chemical and physical diversity of protein nanotube cavities and highlight their potential applications in materials science, specifically in biotechnology. Full article
(This article belongs to the Special Issue Carbon Nanostructures as Promising Future Materials)
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14 pages, 4879 KiB  
Article
Design of Ni(OH)2 Nanosheets@NiMoO4 Nanofibers’ Hierarchical Structure for Asymmetric Supercapacitors
by Junzhu Li, Xin Chang, Xuejiao Zhou and Mingyi Zhang
Nanomaterials 2022, 12(22), 4079; https://doi.org/10.3390/nano12224079 - 19 Nov 2022
Cited by 2 | Viewed by 1189
Abstract
Transition−metal−based materials show great promise for energy conversion and storage due to their excellent chemical properties, low cost, and excellent natural properties. In this paper, through simple strategies such as classical electrospinning, air calcination, and the one−step hydrothermal method, a large area of [...] Read more.
Transition−metal−based materials show great promise for energy conversion and storage due to their excellent chemical properties, low cost, and excellent natural properties. In this paper, through simple strategies such as classical electrospinning, air calcination, and the one−step hydrothermal method, a large area of Ni(OH)2 nanosheets were grown on NiMoO4 nanofibers, forming NiMoO4@Ni(OH)2 nanofibers. The one−dimensional nanostructure was distributed with loose nanosheets, and this beneficial morphology made charge−transfer and diffusion more rapid, so the newly developed material showed good capacitance and conductivity. Under the most suitable experimental conditions, the optimal electrode exhibited the highest specific capacitance (1293 F/g at 1 A/g) and considerable rate capability (56.8% at 10 A/g) under typical test conditions. Most interestingly, the corresponding asymmetrical capacitors exhibited excellent electrochemical cycle stability, maintaining 77% of the original capacitance. NiMoO4@Ni(OH)2 nanofibers were verified to be simple to prepare and to have good performances as energy−storage devices within this experiment. Full article
(This article belongs to the Special Issue Nanostructures for Wastewater Treatment and Energy Conversion)
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13 pages, 2250 KiB  
Article
Sensitivity Enhanced Plasmonic Biosensor Using Bi2Se3-Graphene Heterostructures: A Theoretical Analysis
by Fusheng Du, Kai Zheng, Shuwen Zeng and Yufeng Yuan
Nanomaterials 2022, 12(22), 4078; https://doi.org/10.3390/nano12224078 - 19 Nov 2022
Cited by 8 | Viewed by 1369
Abstract
This study provided a theoretical insight for designing novel plasmonic biosensors using bismuth selenide (Bi2Se3)-Graphene heterostructures. It was a van der Waals (vdWs) stacked configuration composed of gold (Au) film, few quintuple layer (QL) Bi2Se3 and [...] Read more.
This study provided a theoretical insight for designing novel plasmonic biosensors using bismuth selenide (Bi2Se3)-Graphene heterostructures. It was a van der Waals (vdWs) stacked configuration composed of gold (Au) film, few quintuple layer (QL) Bi2Se3 and few-layered graphene. In particular, the proposed biosensor was created by Goos-Hänchen (GH) shift rather than phase, resulting in a more sensitive biosensing response. Under the excitation of 632.8 nm, significant sensitivity enhancement performance was obtained via varying the thickness of Bi2Se3-Graphene heterostructures. The best configuration was 32 nm Au film−2-QL Bi2Se3-3-layer graphene, generating the largest GH shift, as high as −1.0202 × 104 µm. Moreover, the highest detection sensitivity was determined to be 8.5017 × 106 µm/RIU, responding to a tiny refractive index (RI) change of 0.0012 RIU (RIU, refractive index unit). More importantly, our proposed biosensor has shown a theoretical feasibility of monitoring virus samples. For example, there was an efficient linear detection range for severe acute respiratory syndrome coronavirus 2 (SARS-CoV−2, 0~13.44 nanomole (nM)) and its Spike (S) glycoprotein (0~59.74 nM), respectively. It is expected that our proposed plasmonic biosensor has a potential application in performing sensitive detection of SARS-CoV−2. Full article
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