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Polar surface dominated octagonal Sn doped ZnO nanowires and their room-temperature photoluminance properties
摘要： Polar surface dominated Sn doped ZnO nanowires (NWs) with an octagonal shaped cross section have been fabricated by chemical vapor deposition method. The NWs grew along [01 0] direction, and were wrapped by non-polar surface (2 0) and polar surfaces (0001) and (1 1). Planar defects in (0001) plane were formed in the middle of the doped NWs, and strain concentration occurred around the planar defects, which might lower the energy in the wurtzite lattice and thus maintain polar surface dominated configuration. X-ray photoelectron spectroscopy (XPS) and Raman tests reveal that the concentration of Oxygen vacancy (VO) was significantly lowered after doping, which led to the reduced deep level emission (DLE).
关键词： Polar surface,Photoluminance,Sn-doped ZnO Nanowires,Microstructure
更新于2025-09-23 15:23:52
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Synthesis of ZnO nanowires/Au nanoparticles hybrid by a facile one-pot method and their enhanced NO2 sensing properties
摘要： ZnO nanowires (ZNWs) and ZnO nanowires/Au nanoparticles hybrid (Au-ZNWs) with various Au concentrations were synthesized by a facile one-pot hydrothermal method and characterized by XRD, SEM, TEM, XPS, and FTIR. The structural characterization results exhibited that Au nanoparticles were self-assembled onto the surface of ZNWs and the c-axis growth of ZNWs is suppressed by the addition of HAuCl4 in the synthesis of Au-ZNWs hybrid. Gas sensing properties demonstrated the favorite sensing performance could be achieved for 1 mol% Au-ZNWs compared to pure ZNWs and Au-ZNWs with other Au concentrations. The maximum response of 1 mol% Au-ZNWs to 1 ppm NO2 was 31.4 at 150 °C, which was nearly 4 times higher than 8.2 of pure ZNWs. And the shortest response and recovery times could also be achieved by 1 mol% Au-ZNWs in a wide range of operating temperature. Au-ZNWs with various Au concentrations showed better selectivity to NO2 than pure ZNWs. The mechanism of enhanced NO2 sensing performance of Au-ZNWs was investigated by the combination of electronic and chemical sensitizations via Au nanoparticles functionalization.
关键词： NO2,Nanowires,Gas sensor,Au functionalization,ZnO
更新于2025-09-23 15:23:52
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Preparation of Pd/TiO2 nanowires for the photoreduction of CO2 into renewable hydrocarbon fuels
摘要： In this study, various Pd-loaded TiO2 nanowire (Pd/TiO2–NW) catalysts were prepared using the hydrothermal method, and their photocatalytic activity toward the photoreduction of CO2 into methane (CH4) and carbon monoxide (CO) was evaluated. The photocatalysts were characterized by X-ray diffraction, scanning electron microscopy, inductively coupled plasma atomic emission spectroscopy, transmission electron microscopy, UV–vis spectroscopy, X-ray photoelectron spectroscopy and photoluminescence analysis. The addition of Pd on TiO2–NWs can improve the production yield of CO2 photoreduction to CH4 and CO. The 0.5 wt% Pd/TiO2–NWs showed optimal CO and CH4 yields of 50.4 and 26.7 μmol/g, respectively. Moreover, the 0.5 wt% Pd/TiO2–NWs could be used repeatedly with only a small loss of photocatalytic activity noted after 30 days. Furthermore, a mechanism for the photoreduction of CO2 was proposed. Therefore, Pd/TiO2–NWs are an efficient photocatalyst for the reduction of CO2 to CH4 and CO.
关键词： Renewable hydrocarbon fuels,CO2 conversion,Photocatalyst,Pd-loaded TiO2 nanowires
更新于2025-09-23 15:23:52
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Integration of organic/inorganic nanostructured materials in a hybrid nanogenerator enables efficacious energy harvesting via mutual performance enhancement
摘要： Recent reports demonstrate that hybrid energy harvesting devices can efficiently convert ubiquitously available but mostly unexploited ambient energies (e.g., mechanical, chemical, thermal, solar) into usable power that can potentially support a new generation of self-powered electronic systems. In this paper, we present a hybrid organic/inorganic nanogenerator on shim substrates, which integrates both piezoelectric and triboelectric components based on inorganic p-n junction ZnO nanostructures and nanostructured organic polytetrafluoroethylene (PTFE) film, respectively. In this design, individual components can be operated independently or concurrently. Moreover, when operated concurrently, component performance is mutually enhanced, enabling more efficient conversion of mechanical energy into electrical energy in a single press-and-release cycle. When triggered with 25 Hz frequency and 1G acceleration of external force, the piezoelectric nanogenerator (PENG) component generates a peak-to-peak output voltage of 34.8V, which is ～3 times higher than its output when it acts alone. Similarly, the triboelectric nanogenerator (TENG) component generates a peak-to-peak output voltage of 356V under the same conditions, which is higher than its initial output of 280V when acting alone. The nanogenerator unit produces an average peak output voltage of 186 V, current density of 10.02 μA/cm2, and average peak power density of 1.864 mW/cm2 when operated in the hybrid configuration. The device can even produce an average peak-to-peak voltage of ~160V from normal hand movement when placed under a wristband fitness tracker, and ~580V from human walking when placed within the walker’s shoe. The device has been demonstrated to charge commercial capacitors up to a few volts within several seconds.
关键词： nanoplates,energy harvesting,hybrid nanogenerators,nanowires,piezoelectricity,triboelectricity
更新于2025-09-23 15:23:52
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Capillarity-Driven Self-Assembly of Silver Nanowires-Coated Fibers for Flexible and Stretchable Conductor
摘要： The rapid development of smart textiles requires the large-scale fabrication of conductive fibers. In this study, we develop a simple, scalable and low-cost capillary-driven self-assembly method to prepare conductive fibers with uniform morphology, high conductivity and good mechanical strength. Fiber-shaped flexible and stretchable conductors are obtained by coating highly conductive and flexible silver nanowires (Ag NWs) on the surfaces of yarn and PDMS fibers through evaporation-induced flow and capillary-driven self-assembly, which is proven by the in situ optical microscopic observation. The density of Ag NWs and linear resistance of the conductive fibers could be regulated by tuning the assembly cycles. A linear resistance of 1.4 Ω/cm could be achieved for the Ag NWs-coated nylon, which increases only 8% after 200 bending cycle, demonstrating high flexibility and mechanical stability. The flexible and stretchable conductive fibers have great potential for the application in wearable devices.
关键词： flexible,self-assembly,Fiber conductor,stretchable,silver nanowires.
更新于2025-09-23 15:23:52
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Contactless Optical Characterization of Carrier Dynamics in Free-Standing InAs-InAlAs Core-Shell Nanowires on Silicon
摘要： Contactless time-resolved pump-probe and external quantum efficiency measurements were performed on epitaxially grown free-standing wurtzite indium arsenide/indium aluminum arsenide (InAs-InAlAs) core-shell nanowires on Si (111) substrate from 77K to 293K. The first independent investigation of Shockley-Read-Hall, radiative and Auger recombination in InAs-based NWs is presented. Although the Shockley-Read Hall recombination coefficient was found to be at least two orders of magnitude larger than the average experimental values of other reported InAs materials, the Auger recombination coefficient was reported to be ten-fold smaller. The very low Auger and high radiative rates result in an estimated peak internal quantum efficiency of the core-shell nanowires as high as 22% at 77K, making these nanowires of potential interest for high efficiency mid-infrared emitters. A greater than two-fold enhancement in minority carrier lifetime was observed from capping nanowires with a thin InAlAs shell due to passivation of surface defects.
关键词： Auger recombination rate,radiative,Shockley-Read-Hall,Pump-probe spectroscopy,core-shell nanowires,surface/interface recombination velocity,minority carrier lifetime
更新于2025-09-23 15:23:52
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Fe Foil-Guided Fabrication of Uniform Ag@AgX Nanowires for Sensitive Detection of Leukemia DNA
摘要： Herein, we report a novel Fe foil guided, in-situ etching strategy for the preparation of highly uniform Ag@AgX (X = Cl, Br) nanowires (NWs) and applied the photoelectric-responsive materials for sensitive photoelectrochemical (PEC) detection of Leukemia DNA. The Ag@AgX NWs formation process was discussed from the redox potential and Ksp value. The fabricated PEC platform for sensing Leukemia DNA showed good assay performance with a wide linear range (0.1 pM to 50 nM) and low detection limit of 0.033 pM. We envision that our Fe foil-guided synthetic method could be applied to synthesize more photoactive materials for sensitive PEC detections.
关键词： Leukemia DNA,photoelectrochemical detection,in-situ,Br) nanowires,Ag@AgX (X = Cl,etch,Fe foil
更新于2025-09-23 15:23:52
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La-doped p-type ZnO nanowire with enhanced piezoelectric performance for flexible nanogenerators
摘要： In recent years, energy harvesting has attracted considerable attention as a promising method to convert waste energy to useful energy. In particular, piezoelectric energy harvesters are of significant interest, because they have a simple structure and can be used to harvest energy regardless of weather or other environmental conditions. In accordance with the miniaturization trend of electronic devices driven by low power, piezoelectric nanogenerators (PENGs) using various nanostructured materials are being developed. Among them, ZnO nanowires (NWs) are most widely used for the use of PENGs. However, while research on n-type ZnO NWs is extensive, studies on p-type ZnO NWs are insufficient owing to their poor stability. In this study, La-doped p-type ZnO (La:ZnO) NWs were synthesized by a hydrothermal method to expand the applications of p-type ZnO and determine their potential as PENGs. XRD analysis showed that La3+ ions was well doped without the formation of any secondary phases and caused a change in the lattice parameter when compared to that of undoped ZnO. XPS analysis was performed to investigate the surface elemental compositions of La:ZnO NWs, and the morphology of La:ZnO NWs was investigated using SEM and TEM. We further studied the piezoelectric output performance of undoped and La-doped ZnO NWs, and found that La:ZnO NWs showed improved piezoelectric output performance as a result of electron screening effect of the p-type semiconductor.
关键词： p-type ZnO,La-doping,Flexible device,ZnO nanowires,Nanogenerators
更新于2025-09-23 15:23:52
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Enhancement of multi-photon Raman scattering and photoluminescence emission from Li-doped ZnO nanowires
摘要： Uniform Li-doped ZnO nanowires have been fabricated by thermal evaporation method. The ZnO formation and the Li incorporation have been discussed and the formation path of preparation products has also been explained in terms of the stability of Zn and Li vapor in an aerobic atmosphere. The strongest vibration mode at 437.2 cm?1 in the multi-photon Raman scattering of the as-prepared products at room temperature indicates that the Li-doped ZnO nanowires still keep the hexagonal (wurtzite) structure. Raman spectra of Li-doped ZnO with different doping concentrations confirm that the variation of Raman peaks in the range of 550 cm?1～650 cm?1 is caused by the doping of lithium. The photoluminescence property at room temperature shows a blue-shift compared with undoped ZnO in the ultraviolet region. The Gauss fitting analyzed results indicate that the broad-band is composed of one green luminescence (GL) band, one yellow luminescence (YL) band, and one red luminescence (RL) band, respectively. The GL (2.447 eV) could be attributed to the singly ionized oxygen vacancies. The origin of the YL (2.245 eV) could be assigned to the transition of an electron from the conduction band (or a shallow donor) to the Li acceptor level. The RL (1.977 eV) could be assigned to the transitions between a shallow donor (at low temperature) or the conduction band (at higher temperature). Furthermore, the luminescence spectra at low temperature confirm the increase of defect levels like oxygen vacancies.
关键词： li-doped ZnO nanowires,formation process,photoluminescence,multi-photon raman scattering
更新于2025-09-23 15:23:52
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Surface doping of ZnO nanowires with Bi: Density-functional supercell calculations of defect energetics
摘要： Defect calculations using the density and hybrid functionals in combination with the supercell approach are employed to characterize the electrical properties of a number of ZnO nanowires of various thicknesses doped with Bi atoms occupying surface sites. The variation of the differences between the total energies of charged and neutral supercells with the supercell size is studied, which led the authors to devise an extrapolation procedure to obtain reliable defect energetics in the dilute defect limit. The calculated defect formation energies indicate that although the substitution of Bi into Zn or O sites can take place spontaneously under suitable thermodynamic conditions, the substitution into Zn sites is generally more likely. The defect (charge-state) transition energies are computed and parameterized as a function of the nanowire thickness. It is revealed that the substitution of Bi into O (Zn) sites on the surface of ZnO nanowires yields deep acceptor (shallow donor) levels (except for extremely thin nanowires). It is therefore concluded that the incorporation of Bi into the surface of ZnO nanowires results in n-type doping.
关键词： ZnO nanowires,defect energetics,n-type doping,bismuth doping,supercell calculations,density functional theory
更新于2025-09-23 15:23:52