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Au@Ag nanorod horizontal arrays: Self-assembly preparation and in situ monitoring SERS of plasmonic catalytic reaction
摘要： Here, we successfully synthesized silver-coated gold nanorods (Au@Ag NRs) via a facile wet chemical method. The catalytic property of Au@Ag NRs in water solution was much better than that of Au NRs in water solution. To obtain high catalytic properties, we self-assembled a single-layer Au@Ag NR array by evaporation on a silicon wafer. The catalytic activity of the Au@Ag NR array was probed using the reduction of 4-nitrothiophenol. The reaction processes were monitored and identified through in situ surface-enhanced Raman spectroscopy based on the confocal Raman microscope system. This study provides a simple and fast method to improve the catalytic property of the noble nanoparticles.
关键词： In situ monitoring,Self-assembly,Au@Ag nanorods,Plasmonic catalytic reaction,SERS
更新于2025-09-23 15:19:57
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Shape-dependant photocatalytic and antimicrobial activity of ZnO nanostructures when conjugated to graphene quantum dots
摘要： To reduce the bandgap and e-/h+ pairs recombination, zinc oxide nanoflakes (ZnO-NFs) and zinc oxide nanorods (ZnO-NRs) were covalently linked to graphene oxide quantum dots (GQDs). Photocatalytic and antimicrobial activity of ZnO nanohybrids (ZnO-NFs@GQDs and ZnO-NRs@GQDs) were investigated. The formation of the distinct ZnO nanoflakes and ZnO nanorods shaped nanoparticles were evidenced by SEM. The bandgap decreased from 2.98 to 2.61 eV and 3.00 to 2.79 eV for ZnO-NFs@GQDs and ZnO-NRs@GQDs, respectively. Photoluminescence (PL) data showed a similar trend where a larger decrease was obtained for ZnO-NFs@GQDs. Photolysis ruled out adsorption mechanism for the removal of dye. Optical data and PL measurements supported photocatalytic findings that ZnO-NFs@GQDs performed better (80%) than ZnO-NRs@GQDs (18%). ZnO-NRs@GQDs however, showed greater bacterial inhibition when tested against E. coli, P. aeruginosa, B. cereus and S. aureus. The antimicrobial efficiency followed the order: ZnO-NFs < ZnO-NFs@GQDs < ZnO-NRs < ZnO-NRs@GQDs with greater efficiency being against S. aureus. Liquid photocatalysts zinc nanoparticles can thus be used to remove dyes and inhibit bacterial growth in aqueous solution.
关键词： Zinc oxide nanorods,zinc oxide nanoflakes,antimicrobial activity,photocatalysis,graphene quantum dots
更新于2025-09-23 15:19:57
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Effect of annealing temperature of MoO3 layer in MoO3/Au/MoO3 (MAM) coated PbS QDs sensitized ZnO nanorods/FTO glass solar cell
摘要： This research reports fabrication of MoO3/Au/MoO3 (MAM) coated PbS sensitized quantum dot solar cell. ZnO nanorod grown FTO glass substrates were sensitized by PbS quantum dots (PbS QDs/ZnO nanorods/FTO Glass), followed by (MoO3/Au/MoO3) coating. Hydrothermal process was used to grow ZnO nanorods, followed by the deposition of PbS QDs using Successive Ionic Layer Adsorption and Reaction (SILAR). Finally, (MoO3/Au/MoO3) layers were deposited for the back contact. Spin coating was used to deposit MoO3 layers while middle layer of Au was deposited by sputter coating. Three such devices were fabricated with three di?erent annealing temperatures i.e. 100 °C, 150 °C and 200 °C for ?rst MoO3 layer. Scanning Electron Microscopy (SEM) was used for surface morphology of the devices; Energy Dispersive Spectroscopy Analysis (EDS) and X-Ray Di?raction (XRD) techniques were used for elemental and structural analysis, Optical properties of the devices were determined using UV–Visible analysis. Power conversion e?ciency (PCE) of all three devices was obtained to observe devices performance. Improved PCE of 4.617% was obtained by the device with the thermal treatment of 150 °C.
关键词： Quantum dots,ZnO nanorods,MoO3 thin ?lm,PbS quantum dot sensitized Solar Cell
更新于2025-09-23 15:19:57
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Temperature-Controlled Fragmentation and Ripening: Synthesis of ZnSe Nanorods with Variable Dimensions and Crystal Structure Starting from Ultrathin ZnSe Nanowires
摘要： Heavy-metal-free semiconductor nanomaterials have attracted attention because of their importance in both fundamental research and commercial applications. In particular, polarized ?uorescence emission in one-dimensional (1D) semiconductors makes them highly attractive as display materials. Herein, we developed a novel colloidal synthesis approach toward 1D ZnSe nanostructures with controlled size and crystal structure, which we call “temperature-controlled fragmentation and ripening”. First, ultrathin ZnSe nanowires (NWs) with a length of 50?200 nm and diameter of ～1.1 nm were synthesized. ZnSe nanorods (NRs) have been obtained through the fragmentation of these NWs in a controlled step while keeping the same diameter, and the length of the ?nal ZnSe NRs has been tuned in the range of 10?20 nm by moderating the heating procedure. Using a higher temperature for fragmentation allowed us to break down the ZnSe NWs to shorter ZnSe NRs, whereas controlling the ?nal growth temperature of the ZnSe NRs in a subsequent ripening stage allowed us to obtain them in either cubic zinc blende (ZB; at 220 °C) or hexagonal wurtzite (WZ; at 240 °C) crystal structures. This set of growth processes ?ipping from bottom-up to top-down to form ZnSe NRs with controlled length and selection of the ?nal crystal structure (either hexagonal WZ or cubic ZB) provides a novel growth mechanism to synthesize 1D semiconductor nanostructures.
关键词： nanorods,ripening,nanowires,temperature-controlled fragmentation,ZnSe,crystal structure
更新于2025-09-23 15:19:57
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Inverted pyramid Er3+ and Yb3+ Co-doped TiO2 nanorod arrays based perovskite solar cell: Infrared response and improved current density
摘要： In this study, a Yb3+, Er3+ co-doped TiO2 inverted pyramid nanorod (NR) array and a compact TiO2 ?lm are simultaneously fabricated as the mesoporous support layer and electron-blocking layer, respectively, by a one-pot hydrothermal method. The scanning electron microscopy results show that the incorporation of Er3+ and Yb3+ causes changes not only in the growth rate of the NRs, but also in the TiO2 NR morphology. The Er3+, Yb3+ co-doped TiO2 NRs exhibit an inverted pyramidal morphology, which is bene?cial for perovskite permeation and light utilization. Notably, the Er3+, Yb3+ co-doping causes changes in the band gap of TiO2 and leads to 25% increase in the current density. The electrochemical impedance spectroscopy results show that the device based on the doped TiO2 NRs has a higher recombination resistance and a lower transfer resistance than those of the undoped device, and thereby, the doped device exhibits a lower electron recombination rate. In addition, the upconversion Er and Yb co-doped device exhibits 25% higher current density and 17% higher photon-to-electron conversion e?ciency, as revealed by the J-V test results. Moreover, the optimized e?ciency of the TiO2 NR array-based perovskite solar cell is determined to be 10.02%. Furthermore, the Er and Yb co-doped device exhibits a near-infrared response, an e?ciency of 0.1% is achieved under infrared light (800–1100 nm) irradiation. This upconversion material can widen the photovoltaic responses of solar cells into the near-infrared region and improve the utilization of sunlight.
关键词： Infrared response,Yb3+,Er3+ co-doped,TiO2 nanorods,Perovskite solar cell
更新于2025-09-23 15:19:57
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Interaction of ZnO nanorods with plasmonic metal nanoparticles and semiconductor quantum dots
摘要： We model the enhancement of near band edge emission from ZnO nanorods using plasmonic metal nanoparticles and compare it with emission enhancement from ZnO with semiconducting quantum dots. Selected CdSe quantum dots with absorption energies close to those of Ag and Au nanoparticles are chosen to construct model systems with ZnO to comprehend the role of ZnO’s intrinsic defects and plasmonic excitation in realizing the spectrally selective luminescence enhancement. Excitation wavelength dependent photoluminescence spectra along with theoretical models quantifying the related transitions and plasmonic absorption reveal that a complex mechanism of charge transfer between the ZnO nanorods and metal nanoparticles or quantum dots is essential along with an optimal energy band alignment for realizing emission enhancement. The theoretical model presented also provides a direct method of quantifying the relative transition rate constants associated with various electronic transitions in ZnO and their change upon the incorporation of plasmonic nanoparticles. The results indicate that, while the presence of deep level defect states may facilitate the essential charge transfer process between ZnO and the plasmonic nanoparticles, their presence alone does not guarantee UV emission enhancement and strong plasmonic coupling between the two systems. The results offer clues to designing novel multicomponent systems with coupled plasmonic and charge transfer effects for applications in charge localization, energy harvesting, and luminescence enhancement, especially in electrically triggered nanophotonic applications.
关键词： ZnO nanorods,plasmonic metal nanoparticles,semiconductor quantum dots,luminescence enhancement,charge transfer
更新于2025-09-23 15:19:57
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An All Carbon Dye Sensitized Solar Cell: A Sustainable and Low-Cost Design for Metal Free Wearable Solar Cell Devices
摘要： Lightweight carbon electrodes are the new candidates for photovoltaic devices due to their temperature resistivity, ease of fabrication, and skin comfortability. Herein, a sustainable and facile strategy has been proposed for metal free all carbon dye sensitized solar cell (C-DSSC), assembled by stacking carbon front electrode (CFE) and carbon counter electrode (CCE). The CFE demonstrated adequate light transmittance (70-50%) while maintaining efficient photon absorption and charge separation mechanism due to dye coated TiO2 nanorods (P25-R). The graphene dip coated carbon counter electrode (Gr@CCE) possesses remarkable highly electro catalytic activity towards 3 /I ― I ― redox couple with low charge transfer resistance (RCT=0.79 ?). The sustainable design of C-DSSC attained ~6±0.5 % efficiency with high photocurrent density of 18.835 mA. cm-2. The superior performance of C-DSSC is accredited to its improved charge mobility, low internal resistance, and better interfacial electrode contact. The thickness of C-DSSC is ≤3 mm eliminates the need for rigid glass in DSSC.
关键词： Carbon,TiO2 nanorods,Dye sensitized solar cell,Graphene,Electrocatalytic activity
更新于2025-09-23 15:19:57
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Unraveling the dual functional mechanism of light absorption and hole transport of Cu2CdxZn1-xSnS4 for achieving efficient and stable perovskite solar cells
摘要： Broadening the near-infrared (NIR) spectrum of device is critical to further improve the power conversion efficiency (PCE) of the perovskite solar cells (PSCs). In this work, novel Cu2CdxZn1-xSnS4 (CZTS: Cd) film prepared by thermal evaporation method was employed as the NIR light-harvesting layer to complement absorption of the perovskite. At the same time, Au nanorods (NRs) were introduced into the hole transporting layer (HTL) to boost the utilization of CZTS: Cd to NIR light through localized surface plasmon effect. The perovskite/CZTS: Cd and Au NRs integrated PSCs can extend the photoelectric response until to 900 nm. And more, the well matched energy levels between CZTS: Cd and perovskite can effectively extract holes from perovskite and depress the charge-carrier recombination. As a result, the champion PSC device insulating with CZTS: Cd and Au NRs demonstrates a remarkably increased PCE from 19.30% to 21.11%. The modified PSC devices also demonstrate highly improved long time stability. The device retains the PCE of 87% after 500 h even under air with a relative humidity of 85%, implying the superior humidity stability of the devices with CZTS: Cd. This work suggests that perovskite/inorganic integrated structure is a promising strategy to broaden and boost the NIR response of the PSCs.
关键词： Perovskite solar cells,Cu2CdxZn1-xSnS4,Stability,Plasmon,Au nanorods
更新于2025-09-23 15:19:57
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Self-assembled nanorods in YBCO matrix a?? a computational study of their effects on critical current anisotropy
摘要： In order to understand how the doping with self-assembled nanorods of different sizes and concentrations as well as applied magnetic fields affect the critical current anisotropy in YBa2Cu3O7?x (YBCO) thin films close to YBCO c-axis, we present an extensive and systematic computational study done by molecular dynamics simulation. the simulations are also used to understand experimentally measured Jc(θ) curves for BaHfO3, BaZrO3 and BaSnO3 doped YBCO thin films with the help of nanorod parameters obtained from transmission electron microscopy measurements. our simulations reveal that the relation between applied and matching field plays a crucial role in the formation of Jc(θ)-peak around YBCO c-axis (c-peak) due to vortex-vortex interactions. We also find how different concentrations of different size nanorods effect the shape of the c-peak and explain how different features, such as double c-peak structures, arise. In addition to this, we have quantitatively explained that, even in an ideal superconductor, the overdoping of nanorods results in decrease of the critical current. our results can be widely used to understand and predict the critical current anisotropy of YBco thin films to improve and develop new pinscapes for various transport applications.
关键词： critical current anisotropy,molecular dynamics simulation,YBCO,flux pinning,self-assembled nanorods
更新于2025-09-23 15:19:57
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Investigation into effect of coupled resonance phenomenon towards sensitivity enhancement of SAW conductivity sensors integrated with ZnO nanorods
摘要： In this work, FEM simulation was used to investigate the sensitivity of a one-port surface acoustic wave (SAW) resonator sensor to changes in electrical conductivity of the sensing medium composed of ZnO nanorods offering elastic loading on the surface of the resonator. A system of coupled resonators was formed when the height of the ZnO nanorods attached to the surface of the resonator was adjusted such that the resonant frequency of the nanorod approached the original resonant frequency of the SAW resonator. It was observed that the use of ZnO nanorods of resonant dimensions as sensing medium could enhance the sensitivity of the composite SAW sensor to changes in electrical conductivity of the sensing medium by up to 79 times. The comparatively higher sensitivity of the SAW conductivity sensor utilizing ZnO nanorods at resonant dimensions as sensing medium was attributed to the fact that the system of coupled resonators thus formed operates at a state of high sensitivity to changes induced in piezoelectric stiffening of the substrate during SAW propagation. The observations from FEM simulation conducted in the present work suggests strong prospects for the use of coupled resonance phenomenon at nanoscale for enhancing the sensitivity of conductivity-based SAW gas sensors and UV detectors employing 1-D ZnO nanostructures as sensing medium.
关键词： ZnO nanorods,sensitivity enhancement,SAW resonator,coupled resonance,FEM simulation
更新于2025-09-23 15:19:57