Nanowire Surface Research Articles

Ultrahigh-mobility microbial cytochrome nanowires generate power from humidity.

Mixed electronic-ionic conductors are crucial for various technologies, including harvesting power from humidity in a durable, self-sustainable, manner unrestricted by location or environment1,2. Biological proteins have been proposed as mixed conductors for 50 years3,4. Recently, Geobacter sulfurreducens pili filaments have been claimed to act as nanowires to generate power5,6. Here, we show that the power is generated by G. sulfurreducens-produced cytochrome OmcZ nanowires that show 20,000-fold higher electron conductivity than pili7. Remarkably, nanowires show ultrahigh electron and proton mobility (>0.25 cm2/Vs), owing to directional charge migration through seamlessly-stacked hemes and a charged, hydrogen-bonding surface, respectively. AC impedance spectroscopy and DC conductivity measurements using four-probe van der Pauw and back-gated field-effect-transistor devices reveal that humidity increases carrier mobility by 30,000-fold. Cooling halves the activation energy, thereby accelerating charge transport. Electrochemical measurements identify the voltage and mobilities required to switch pure electronic conduction to mixed conduction for power generation. The high aspect ratio (1:1000) and hydrophilic nanowire surface captures moisture efficiently to reduce oxygen reversibly, generating large potentials (>0.5 V) necessary to sustain high power. Our studies establish a new class of biologically-synthesized, low-cost and high-performance mixed-conductors and identify key design principles for improving power output using highly-tunable electronic and protein structures.

Inverse-designed multi-diameter InAs nanowire array ultra-broadband photodetectors enhanced by localized surface plasmon resonances

Multi-diameter InAs nanowire array ultra-broadband photodetectors are inversely designed and further enhanced by localized surface plasmon resonances. The nanowire diameters are carefully selected by the particle swarm optimization algorithm within the range of 100-800 nm. The multi-diameter nanowire array exhibits high absorption over 80% within a broadband wavelength range of 0.5-3.42 µm, much wider and flatter than that of the single-diameter counterpart, which is attibuted to the superposition of multiple absorption peaks as well as the extension of absorption to longer wavelengths. By introducing indium tin oxide nanoparticles onto the nanowire surface, the lowest absorption is further raised to 87% within a broad wavelength range of 0.55-3.5 µm due to the localized surface plasmon resonances, and the dark current density is substantially reduced from 214 mA/cm2 to 83 mA/cm2 due to the large depletion region. This work may pave the way for the development of ultra-broadband high-responsivity infrared photodetectors.

Selective electroreduction of CO2 to C2+ products on cobalt decorated copper catalysts

Cu-catalyzed electrochemical CO2 reduction reaction (CO2RR) to multi-carbon (C2+) products is often plagued by low selectivity because the adsorption energies of different reaction intermediates are in a linear scaling relationship. Development of Cu-based bimetallic catalysts has been considered as an attractive strategy to address this issue; however, conventional bimetallic catalysts often avoid metals with strong CO adsorption energies to prevent surface poisoning. Herein, we demonstrated that limiting the amount of Co in CuCo bimetallic catalysts can enhance C2+ product selectivity. Specifically, we synthesized a series of CuCox catalysts with trace amounts of Co (0.07-1.8 at%) decorated on the surface of Cu nanowires using a simple dip coating method. Our results revealed a volcano-shaped correlation between Co loading and C2+ selectivity, with the CuCo0.4% catalyst exhibiting a 2-fold increase in C2+ selectivity compared to the Cu nanowire sample. In situ Raman and Infrared spectroscopies suggested that an optimal amount of Co could stabilize the Cu oxide/hydroxide species under the CO2RR condition and promote the adsorption of CO, thus enhancing the C2+ selectivity. This work expands the potential for developing Cu-based bimetallic catalysts for CO2RR.

Selective oxidation of glycerol mediated by surface plasmon of gold nanoparticles deposited on titanium dioxide nanowires

This paper describes an alternative method for the in situ synthesis of gold nanoparticles (AuNPs) with a particle size of less than 3 nm, using nanoreactors formed by reverse micelles of 1,4-bis-(2-ethylhexyl) sulfosuccinate sodium (AOT) and nanoparticle stabilization with l-cysteine, which favor the preparation of nanoparticles with size and shape control, which are homogeneously dispersed (1% by weight) on the support of titanium dioxide nanowires (TNWs). To study the activity and selectivity of the prepared catalyst (AuNPs@TNWs), an aqueous solution of 40 mM glycerol was irradiated with a green laser (λ = 530 nm, power = 100 mW) in the presence of the catalyst and O2 as an oxidant at 22 °C for 6 h, obtaining a glycerol conversion of 86% with a selectivity towards hydroxypyruvic acid (HA) of more than 90%. From the control and reactions, we concluded that the Ti–OH groups promote the glycerol adsorption on the nanowires surface and the surface plasmon of the gold nanoparticles favors the selectivity of the reaction towards the hydroxypyruvic acid.

In vivo biocompatibility of a new hydrophobic coated Al/Al2O3 nanowire surface on stents

BackgroundIntima proliferation and in-stent restenosis is a challenging situation in interventional treatment of small vessel obstruction. Al/Al2O3 nanowires have been shown to accelerate vascular endothelial cell proliferation and migration in vitro, while suppressing vascular smooth muscle cell growth. Moreover, surface modification of Al/Al2O3 nanowires with poly[bis(2,2,2-trifluoromethoxy)phosphazene (PTFEP) coating enables further advantages such as reduced platelet adhesion. Therefore, the study's goal was to compare the biocompatibility of novel Al/Al2O3 + PTFEP coated nanowire bare-metal stents to uncoated control stents in vivo using optical coherence tomography (OCT), quantitative angiography and histomorphometric assessment. Methods15 Al/Al2O3 + PTFEP coated and 19 control stents were implanted in the cervical arteries of 9 Aachen minipigs. After 90 days, in-stent stenosis, thrombogenicity, and inflammatory response were assessed. Scanning electron microscopy was used to analyse the stent surface. ResultsOCT analysis revealed that neointimal proliferation in Al/Al2O3 + PTFEP coated stents was significantly reduced compared to control stents. The neointimal area was 1.16 ± 0.77 mm2 in Al/Al2O3 + PTFEP coated stents vs. 1.98 ± 1.04 mm2 in control stents (p = 0.004), and the neointimal thickness was 0.28 ± 0.20 vs. 0.47 ± 0.10 (p = 0.003). Quantitative angiography showed a tendency to less neointimal growth in coated stents. Histomorphometry showed no significant difference between the two groups and revealed an apparent inflammatory reaction surrounding the stent struts. ConclusionsAt long-term follow-up, Al/Al2O3 + PTFEP coated stents placed in peripheral arteries demonstrated good tolerance with no treatment-associated vascular obstruction and reduced in-stent restenosis in OCT. These preliminary in vivo findings indicate that Al/Al2O3 + PTFEP coated nanowire stents may have translational potential to be used for the prevention of in-stent restenosis.

Heat transfer and visualization of flow boiling on nanowire surfaces in the microchannel

Enhancing heat transfer efficiency is crucial in heat exchange equipment. Although previous studies have focused on developing micro/nano-structured surfaces, further exploration into how surface structure can improve heat transfer efficiency (H) by altering bubble dynamics is still needed. This study aimed to innovatively analyze the impact of titanium carbide (TiC) nanowire heights—specifically 4 µm and 12 µm—on boiling heat transfer performance. Conducted under varying heat flux (Q) (50–200 W/m2) and mass flux (G) (200–300 kg/m2·s), our experiments assessed H, pressure drop (P), and local boiling curves. Using a high-speed camera, we observed complex periodic flow patterns on the 4 µm nanowire surface, including elongated bubble formation, expansion, local dryout, and subsequent fluid rewetting. Results showed that the 12 µm nanowire surface increased H by up to 19.84 % in single-phase conditions, while the 4 µm nanowire surface increased H by up to 27.9 % in two-phase conditions. These findings highlight the significant role of nanowire length and arrangement in optimizing boiling heat transfer performance. This work lays a foundation for further investigations into diverse nanowire materials and configurations.

Electronic perturbation of Cu nanowire surfaces with functionalized graphdiyne for enhanced CO2 reduction reaction

Abstract Electronic perturbation of Cu catalysts surface is crucial for optimizing electrochemical CO2 reduction activity, yet still poses great challenges. Herein, nanostructured Cu nanowires (NW) with fine-tuned surface electronic structure are achieved via surface encapsulation with electron-withdrawing (–F) and -donating (–Me) group-functionalized graphdiynes (R-GDY, R = –F and –Me), and the resulting catalysts, denoted as R-GDY/Cu NW, display distinct CO2 reduction performances. In-situ electrochemical spectroscopy revealed that the *CO (a key intermediate of the CO2 reduction reaction) binding affinity and consequent *CO coverage positively correlate to the Cu surface oxidation state, leading to the favorable C–C coupling on F-GDY/Cu NW over Me-GDY/Cu NW. Electrochemical measurements corroborate the favorable C2H4 production with an optimum C2+ selectivity of 73.15% ± 2.5% observed for F-GDY/Cu NW, while the predominant CH4 production is favored by Me-GDY/Cu NW. Furthermore, leveraging the *Cu–OH/*CO ratio as a descriptor, mechanistic investigation reveals that the protonation of distinct adsorbed *CO facilitated by *Cu–OH is crucial for the selective generation of C2H4 and CH4 on F-GDY/Cu NW and Me-GDY/Cu NW, respectively.

Enhancing SERS sensitivity of semiconductors through constructing CuO@TiO2 heterojunctions via atomic layer deposition

Semiconductors hold great promise for surface-enhanced Raman scattering (SERS) applications. Various strategies have been proposed to address the challenge of low SERS sensitivity in semiconductors, with the construction of heterojunctions being among the most effective approaches. In this study, CuO@TiO2 heterojunctions were fabricated by depositing a precisely controlled layer of TiO2 film onto the surface of CuO nanowires (CuO NWs) using the atomic layer deposition (ALD) technique. This approach significantly enhances the SERS sensitivity of CuO NWs, and the SERS performance of the semiconductor heterojunction can be further optimized by accurately adjusting the thickness of TiO2. The SERS activity exhibits systematic variations with the TiO2 thickness across the CuO@TiO2-Rhodamine 6G (R6G) system, with the optimal SERS performance of the heterojunction substrate achieved at a TiO2 thickness of 250 cycles. This finding highlights the substantial influence of TiO2 coating thickness on the photo-induced charge transfer (PICT) processes within the CuO@TiO2-R6G system. Furthermore, CuO@TiO2 heterojunctions demonstrate exceptional stability and uniformity. As a result, this study holds significant importance in enhancing the SERS performance of oxide semiconductors, designing optimal semiconductor heterojunction SERS substrates, and investigating thickness-dependent charge transfer mechanisms in semiconductors.

Insulated π-Conjugated Azido Scaffolds for Stepwise Functionalization via Huisgen Cycloaddition on Metal Oxide Surfaces.

In organic-inorganic hybrid devices, fine interfacial controls by organic components directly affect the device performance. However, fabrication of uniformed interfaces using π-conjugated molecules remains challenging due to facile aggregation by their strong π-π interaction. In this report, a π-conjugated scaffold insulated by covalently linked permethylated α-cyclodextrin moiety with an azido group is synthesized for surface Huisgen cycloaddition on metal oxides. Fourier-transformed infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy confirm the successful immobilization of the insulated azido scaffold on ZnO nanowire array surfaces. Owing to the highly independent immobilization, the scaffold allows rapid and complete conversion of the surface azido group in Huisgen cycloaddition reactions with ethynyl-terminated molecules, as confirmed by FT-IR spectroscopy monitoring. Cyclic voltammetry analysis of modified indium tin oxide substrates shows the positive effects of cyclic insulation toward suppression of intermolecular interaction between molecules introduced by the surface Huisgen cycloaddition reactions. The utility of the scaffold for heterogeneous catalysis is demonstrated in electrocatalytic selective O2 reduction to H2O2 with cobalt(II) chlorin modified fluorine doped tin oxide electrode and photocatalytic H2 generation with iridium(III) dye-sensitized Pt-loadedTiO2 nanoparticle. These results highlight the potential of the insulated azido scaffold for a stepwise functionalization process, enabling precise and well-defined hybrid interfaces.

Non-completely selenized Cu-OSe nanowires as potassium-philic host for anode-free potassium metal batteries

In contrast to conventional potassium-metal batteries (PMBs), anode-free configurations can greatly enhance the gravimetric/volumetric energy densities and provide maximum safety. However, realizing K metal plating/stripping on a bare current collector with high reversibility is challenging since the substrates usually suffer from high nucleation overpotential, K dendrites and low Coulombic efficiency (CE). Herein, long lifespan anode-free PMBs were realized by using a non-completely selenized Cu-OSe nanowires (NWs) as potassium-philic host. It is found that the Cu-OSe active sites provide a low energy barrier for K nucleation. Additionally, the low K+ transport energy promotes facile K diffusion behavior on Cu-OSe NWs surface. Thus, Cu-OSe NWs achieves high reversibility of K plating/stripping over 950 h in K//K symmetric cells at 1 mA cm–2/1 mAh cm–2. The constructed potassium-metal full cell K0.5MnO2//Cu-OSe NWs with K plating capacity of 10 mAh cm−2 achieves over 520 cycles with high capacity retention of 81.8 %, and the corresponding anode-free battery acquired a capacity retention of 63.5 % over 200 cycles. The fundamental understanding on the effect of Cu-OSe active sites on facile and uniform K deposition will provide guidelines for designing future commercial long lifespan anode-free PMBs.

Constructing inkjet printed dielectric elastomers with modified silicon carbide nanowire surfaces to enhance electromechanical performance

AbstractDielectric elastomers (DEs), have attracted interest because they can replicate the behavior of muscles. They can change shape when subjected to an electric field. A novel DE is proposed in this study that incorporates silicon carbide (SiC) nanowires into silicone rubber (SR). The nanowires were propagated using polycarbosilane via a chemical vapor reaction (CVR). A boronate polymer was employed to promote compatibility between SR and SiC nanowires which modified the nanowire surfaces, leveraging a strong adhesive quality of the catechol moiety. Electrohydrodynamic (EHD) inkjet printing was then used to form the DEs into various shapes. These DEs had substantial dielectric constants of the order of 4.46. Significantly, one of the DEs achieved the highest actuated area strain of 20.36% in an electric field of 16.5 V/μm, demonstrating excellent driving performance. Furthermore, when used the fabricated DEs showed pronounced long‐term stability, meaning they are capable of finding applications in artificial intelligence, biomimetics, aerospace, and other disciplines.Highlights The SiC nanowires were obtained through a chemical vapor reaction. A boronate polymer with catechol moiety was used to modify the SiC nanowires. DEs were formed various shapes by inkjet printing. DEs achieved very large actuated strains of up to 20.36% at 16.5 V/μm.

A Dual-Function AgNW@COF SERS Membrane for Organic Pollutant Removal and Simultaneous Concentration Determination.

Surface enhanced Raman spectroscopy (SERS) is a highly sensitive analytical detection method commonly employed in biochemical and environmental analysis. Nevertheless, the rapid movement of analytes and interfering components in flow systems can impact the real-time, online detection capability of Raman spectroscopy. To address this issue, we developed an innovative approach utilizing covalent organic framework (COF), a robust porous material with excellent water stability, to coat the surface of Ag nanowire (AgNW) for synthesizing AgNW@COF hybrid. The regular pores of the COF serve to effectively eliminate large interfering molecules while facilitating the efficient transport of specific analytes to SERS hot spots. Additionally, the fluid flow-induced scouring effect aids in excluding interfering molecules from the surface of AgNW. By incorporating AgNW@COF into a bifunctional filter membrane with simultaneous filtration and sensing capabilities, we had achieved efficient purification of organic pollutants as well as real-time identification of pollutant species and concentration.

Room temperature hydrogen gas sensor based on Pd decorated bridging GaN nanowires

A highly sensitive and low-power consumption hydrogen (H2) gas sensor based on palladium nanoparticles (Pd NPs) decorated bridging GaN nanowires (NWs) has been fabricated, which can be used for H2 detection at room temperature (RT). The bridging GaN NWs growth across the deep trench of GaN coated sapphire substrate were prepared by Metal-organic Chemical Vapor Deposition (MOCVD), and Pd NPs were deposited on the surface of GaN NWs using magnetron sputtering. The characterizations of the structure and morphology of Pd-GaN NWs indicated that the Pd NPs were successfully loaded on the surface of GaN NWs. The sensors with different Pd thickness (2 nm, 5 nm, 10 nm, and 15 nm) were measured at RT (∼ 25 ℃), with H2 concentrations varying from 1 to 10,000 ppm. When the Pd thickness is 10 nm, the H2 response reaches its maximum, has a fast response time (∼3 s toward 10,000 ppm H2) and a low detection limit (LOD) of 42.2 ppb H2. Moreover, the sensor has excellent repeatability, superior H2 selectivity, relatively good humidity-tolerant and long-term stability. In addition, H2 sensing characteristics at different self-heating power (1.9 mW, 6.6 mW, 18.4 mW, and 36.1 mW) were also measured, and found that the H2 response increased with the increase of self-heating power. The fabricated H2 sensor with low-power consumption (without heater or illumination) have a wide application in portable device or Internet of Things (IoT) system.

Bottom-Up Assembling Hierarchical Enamel-Like Bulk Materials with Excellent Optical and Mechanical Properties for Tooth Restoration.

Enamel has good optical and mechanical properties because of its multiscale hierarchical structure. Biomimetic construction of enamel-like 3D bulk materials at nano-, micro-, mesh- and macro-levels is a challenge. A novel facile, cost-effective, and easy large-scale bottom-up assembly strategy to align 1D hydroxyapatite (HA) nanowires bundles to 3D hierarchical enamel structure with the nanowires bundles layer-by-layer interweaving orientation, is reported. In the strategy, the surface of oleate templated ultralong HA nanowires with a large aspect ratio is functionalized with amphiphilic 10-methacryloyloxydecyl dihydrogen phosphate (MDP). Furtherly, the MDP functionalized HA nanowire bundles are assembled layer-by-layer with oriented fibers in a single layer and cross-locked between layers at a certain angle at mesoscale and macroscale in the viscous bisphenol A-glycidyl methacrylate (Bis-GMA) ethanol solution by shear force induced by simple agitation and high-speed centrifugation. Finally, the excessive Bis-GMA and ethanol are removed, and (Bis-GMA)-(MDP-HA nanowire bundle) matrix is densely packed under hot pressing and polymerized to form bulk enamel-like materials. The composite has superior optical properties and comparable comprehensive mechanic performances through a combination of strength, hardness, toughness, and friction. This method may open new avenues for controlling the nanowires assembly to develop hierarchical nanomaterials with superior properties for many different applications.

Improved near-resonant two photon absorption of α-MnO2 nanowires surface functionalized reduced graphene oxide sheets

The versatile study of graphene derivatives has resurgence of interest on understanding its nonlinear optical response at different nanoscales. Nanostructured manganese dioxide: reduced graphene oxide (MnO2: rGO) hybrids were synthesized by reduction method by varying the content of rGO (5, 10, 15 & 20 wt%). X-ray Photoelectron Spectroscopy studies confirmed the surface functionalization of MnO2 on rGO. Field Emission Scanning Electron Microscopy (FESEM) and High-Resolution Tunnelling Electron Microscopy (HRTEM) witness that with respect to the content of rGO, the morphology of MnO2 varies radically from clusters to nanorods to nanowires over the surface of rGO sheets. Ground state absorption spectra of the hybrids have absorption edge at 268 nm corresponding to combined metal oxide charge transfer between rGO (π-π* transition of CC and n-π transition of C-O bonds) and MnO2 (d-d transition). Moreover, hierarchical MnO2 nanowire network resided on 2D rGO sheets involves broad absorption at the visible spectral domain due to polaron transition as well the localization of π- π* transited electrons that facilitates the probability of occurrence of excited state absorption. Intensity dependent open aperture Z-scan technique of the prepared hybrids using Q-switched Nd: YAG 532 nm nanopulsed laser reveals unusual transitions and enhanced nonlinear absorption. MnO2:(5 wt%) rGO shows saturable absorption (SA) at low intensity and changeover dynamically to reverse saturable absorption (RSA) at higher intensity. MnO2:(10 & 15 wt%) rGO exposes coupled nonlinear absorption (SA + RSA) owing to the combined effect of graphene (π-states) and MnO2 (σ-states). MnO2:(20 wt%) rGO exhibits a stronger RSA ascribed to sequential two photon absorption. The third-order nonlinear absorption coefficient and limiting threshold of MnO2: rGO (20 wt%) are 4.04 ×10-10 m/W and 0.84 ×1012 W/m2, which shows five-fold increase compared to bare rGO and MnO2. The obtained results propose that the optical nonlinearity of MnO2 nanowires surface functionalized rGO sheets can significantly be tuned to meet the requirements for fabricating laser safety devices.

Microscopic insights into metal diffusion and ohmic contact formation in delta-doped GaAs/(Al,Ga)As core/shell nanowires

Semiconductor nanowires (NWs) are promising candidates for use in electronic and optoelectronic applications, offering numerous advantages over their thin film counterparts. Their performance relies heavily on the quality of the contacts to the NW, which should exhibit ohmic behavior with low resistance and should be formed in a reproducible manner. In the case of heterostructure NWs for high-mobility applications that host a two-dimensional electron gas, ohmic contacts are particularly challenging to implement since the NW core constituting the conduction channel is away from the NW surface. We investigated contact formation to modulation-doped GaAs/(Al,Ga)As core/shell NWs using scanning transmission electron microscopy, energy dispersive x-ray spectroscopy and electron tomography to correlate microstructure, diffusion profile and chemical composition of the NW contact region with the current–voltage (I–V) characteristics of the contacted NWs. Our results illustrate how diffusion, alloying and phase formation processes essential to the effective formation of ohmic contacts are more intricate than in planar layers, leading to reproducibility challenges even when the processing conditions are the same. We demonstrate that the NW geometry plays a crucial role in the creation of good contacts. Both ohmic and rectifying contacts were obtained under nominally identical processing conditions. Furthermore, the presence of Ge in the NW core, in the absence of Au and Ni, was found as the key factor leading to ohmic contacts. The analysis contributes to the current understanding of ohmic contact formation to heterostructure core/shell NWs offering pathways to enhance the reproducibility and further optimization of such NW contacts.

Effect of crystal orientation on the scratching behavior of γ-TiAl alloy nanowires by molecular dynamics simulation

In micro-and-nanomachining, crystal orientation effects significantly influence the plastic deformation, mechanical response, and temperature profile of nanowire materials. This study utilizes molecular dynamics simulation to investigate the process of surface scratching on γ-TiAl alloy nanowires under six different crystal orientations. The results reveal that the evolution of internal microscopic defects during the surface scratching process is heavily affected by crystal orientation, resulting in distinct dislocation motion-induced shear deformation and extrusion removal by the tool. These factors determine variations in both the shape of the nanowire's surface pile-up and the overall degree of workpiece deformation. Among all cases examined, (001)[1‾1‾0] crystal orientation exhibits easier removal of atoms with minimal internal defects, while (110)[11‾0] crystal orientation shows maximum atom removal without significant overall deformation, both cases demonstrate superior surface morphology and subsurface quality. Furthermore, stress and temperature profiles within abraded atoms and inside the workpiece depend on crystal orientation. These findings provide valuable insights for characterizing surface damage in γ-TiAl alloy nanowires as well as facilitating the preparation of surface nano-channels.

The enhancement of infrared characterization of passivated InAs nanowires

Indium arsenide (InAs) nanowires (NWs) show significant advantages in optoelectronic devices due to their excellent electronic and optical properties. While the surface states affect such outstanding properties, and the performance of optoelectronic devices can be further optimized by modulating the surface state. Herein, the adsorption and substitution properties and the optoelectronics response of passivated InAs NWs are studied using first-principles calculations combined with nonequilibrium Green's function (NEGF). The results show that O atom adsorption can reduce the band gap and improve infrared absorption of InAs NWs. Meanwhile, for the O atom substitution model, the impurity energy level appears near the Fermi level of InAs NWs, and for a higher concentration O atoms substitution, the semiconduction properties of the InAs NWs are destroyed. We also choose the Au, Cs, Bi, Sn, and Y atoms as decoration atoms to passivate InAs NWs, and compared with the intrinsic InAs NW surface model, the energy bands gap of the metal-atoms adsorption models all show a decreasing trend in addition to Au-atom adsorption, and the absorption coefficients of InAs NWs adsorbed by several atoms such as Cs, Sn, Bi, and Y in the infrared region have redshifts in different degrees. The absorption coefficients of InAs NWs adsorbed by several metal atoms, Sn, Bi, and Y, are higher in the infrared region compared to that of InAs NW adsorbed by O atom. After the screening of materials, we select InAs NWs adsorbed with Cs, Bi, Sn, and Y atoms with good infrared absorption characteristics for the performance study of optoelectronic devices and it is shown that the InAs NW devices with adsorbed Bi and Sn atoms have the optimal performance with low dark current and high photocurrent.

Electronic Structure of Mg-, Si-, and Zn-Doped SnO2 Nanowires: Predictions from First Principles.

We investigated the electronic structure of Mg-, Si-, and Zn-doped four-faceted [001]- and [110]-oriented SnO2 nanowires using first-principles calculations based on the linear combination of atomic orbitals (LCAO) method. This approach, employing atomic-centered Gaussian-type functions as a basis set, was combined with hybrid density functional theory (DFT). Our results show qualitative agreement in predicting the formation of stable point defects due to atom substitutions on the surface of the SnO2 nanowire. Doping induces substantial atomic relaxation in the nanowires, changes in the covalency of the dopant-oxygen bond, and additional charge redistribution between the dopant and nanowire. Furthermore, our calculations reveal a narrowing of the band gap resulting from the emergence of midgap states induced by the incorporated defects. This study provides insights into the altered electronic properties caused by Mg, Si, and Zn doping, contributing to the further design of SnO2 nanowires for advanced electronic, optoelectronic, photovoltaic, and photocatalytic applications.

A graphene-CuNWs@PAMPS mixed aerogel for composite phase change materials with high thermal conductivity and excellent solar-thermal to electrical conversion

Phase change materials could store and release heat energy through phase change. However, the shortcomings of low thermal conductivity in the photothermal conversion process and easy leakage in the solid-liquid conversion seriously hinder the application of heat energy utilization. Graphene had high thermal conductivity, and it was an ideal material for improving the solar absorption, solar energy conversion and thermal conductivity of phase change materials. In this paper, a graphene aerogel composed of copper nanowires (CuNWs)/2-acrylamide-2-methylpropanesulfonic acid (AMPS) was designed. The thermal conductivity and shape stability of phase change materials for solar-thermal-electrical conversion applications were enhanced by composite CuNWs. Furthermore, PAMPS was coated on the surface of copper nanowires to avoid the oxidation of copper nanowires, and the sulfonic acid group of PAMPS was used to induce CuNWs to disperse uniformLy on the graphene sheets, which further constructed a good conductive network. After vacuum impregnation of PW, the best thermal conductivity phase change composite (PW-CuNWs@PAMPS-GA(1:1)) was obtained. The PCC loaded with CuNWs with the same graphene content achieved a thermal conductivity of 1.46 W/(m·K) and a high latent heat of 206.8 J/g. The latent heat retention rate was as high as 99.57 %. The photothermal conversion efficiency of PW-CuNWs@PAMPS-GA(1:1) was remarkable at 96.4 %. Due to its excellent solar-thermal-electrical conversion efficiency, the output voltage and output current were 800.8 mV and 85.8 mA, respectively, at a solar analog intensity of 5 kW/m2. Even after the sunlight was stopped, the voltage output could be maintained for a while by releasing the heat energy stored in the phase change composite.