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Graphene oxide/ZnO nanorods/graphene oxide sandwich structure: The origins and mechanisms of photoluminescence
摘要： In this paper, we present the structural and optical properties of Graphene oxide/ZnO nanorods/graphene oxide (GO/ZnO nanorods/GO) nanocomposites prepared via a hydrothermal method on Si (100) substrate. The X-ray diffraction measurements (XRD) confirm that the prepared samples are of hexagonal wurtzite structure with crystallite size around 50-60 nm. It was obvious from scanning electron microscopy (SEM) that by incorporating the ZnO nanorods between the inter-layer of GO confirmed the formation of sandwich-like nanocomposites structure. ZnO nanorods interaction with GO is displayed by the different vibrational frequencies in fourier transform infrared spectroscopy (FTIR). The UV-Vis spectrum reveals the strongest absorption was observed around 370 nm, while calculating optical band gap energy (Eg) of GO/ZnO NRs/GO was found to be 3.15 eV. The photoluminescence (PL) measurements indicates that the ZnO nanorods have a strong visible emission centered at 559 nm attributed to the presence of impurities in the form of oxygen vacancies. After the nanorods were covered with GO layers, the PL intensity of the nanocomposite is quenched and shifted due to charge-transfer process. Consequently, the obtained results may lead to better performance for the optoelectronic applications.
关键词： ZnO nanorods,hydrothermal method,excitation effect,graphene oxide
更新于2025-11-14 15:25:21
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Sub-ppm acetone gas sensing properties of free-standing ZnO nanorods
摘要： In this paper, ZnO nanorods were synthesized by low cost and simple wet chemical method and used as a highly sensitive acetone gas sensor with detection limit as low as 25 ppb which makes the sensor a promising choice for various applications. The fabricated sensor showed a response value of 1.75 towards 25 ppb acetone at optimum working temperature of 320 °C with a response time of 30s. However, the sensor showed response value of 60 towards 50 ppm acetone with a response time of 15 s. The grown ZnO nanorods were examined by scanning electron microscopy (SEM) and X-ray diffraction (XRD) for morphology and crystallinity characterization. According to the SEM images, freestanding nanorods with mean diameter of 80 nm and mean length greater than 1.5um were obtained with highly preferential c-axis orientation.
关键词： Sub-ppm sensing,Gas sensor,Acetone,ZnO Nanorods,Hydrothermal
更新于2025-09-23 15:22:29
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Effect of Zinc Oxide nanorods on the structural, thermal, dielectric and electrical Properties of Polyvinyl alcohol /Carboxymethyle Cellulose composites
摘要： ZnO nanorods were prepared by chemical vapor deposition (CVD) have lengths ranging between 104.12 and 307.64 nm and diameters ranging between 21.17 and 55.88nm determined by transmission electron microscopy (TEM). Polyvinyl alcohol/carboxymethyl cellulose nanocomposites and Zinc oxide (ZnO) were prepared by casting method. The prepared samples were characterized by various methods. The results of XRD analysis depict the amorphous nature of these polymer samples and the degree of amorphousity is increased due to the addition process. The interaction of the ZnO NRs with the PVA/CMC blend was identified by Fourier transforms infrared spectroscopy (FTIR). The dispersion of dopant within the polymer matrix was supported by scanning electron microscopy (SEM). DSC and TGA was utilized to study the thermal behavior of the films and the highest conducting polymer material is lower the glass transition temperature. The conductivity and dielectric behaviors were analyzed by complex impedance spectroscopy as a frequency function at different temperature. The ac conductivity is found to obey Jonscher’s law, whereas dc conductivity is seen to exhibit Arrhenius behavior and increases with temperatures and the activation energy of the films with an increasing of ZnO NRs content was decreased. The dielectric properties of pure blend and nanocomposites have been enhanced due to the addition of ZnO NRs and are found to be highly temperature dependent. The frequency exponent (s) have been well fitted with the proposed correlation equation of the barrier hopping model. Significant increase in dc and ac conductivities in these nanocomposites samples makes them a potential candidate for electrochemical device applications.
关键词： AC and Dielectric parameters.,TEM,FT-IR,ZnO nanorods,SEM
更新于2025-09-23 15:22:29
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Photoluminescence Immunosensor Based on Bovine Leukemia Virus Proteins Immobilized on the ZnO Nanorods
摘要： Bovine leukaemia virus (BLV) proteins gp51, which are serving as antigens for specific antibodies against BLV proteins (anti-gp51), were applied as biological recognition part in the design of immunosensor devoted for the determination of anti-gp51. The efficiency of the immobilization of BLV proteins gp51 on ZnO nanorod (ZnO-NR) modified glass (ZnO-NR/glass) surface was evaluated. The formation of antigen-antibody complex on the ZnO/glass modified by the BLV proteins gp51 (gp51/ZnO-NR/glass) was investigated by the determination of changes in ZnO photoluminescence. The applicability of gp51/ZnO-NR/glass in the design of photoluminescence based immunosensor was evaluated. Bovine serum albumin (BSA) was applied for the modification of sensing gp51 layer in order to form gp51&BSA layer with advanced selectivity. Polyallylamine hydrochloride (PAH) was applied in order to improve the immobilization of gp51 and BSA based sensing layer (gp51&BSA) on the surface of ZnO-NR/glass. PAH was applied during the formation of gp51&BSA/PAH/ZnO-NR/glass structure. Some aspects of the mechanism of interaction between biomolecules (gp51, bovine serum albumin (BSA) and anti-gp51) and ZnO-NR during the preparation and action of gp51&BSA/ZnO-NR/glass- and gp51&BSA/PAH/ZnO-NR/glass-based immunosensors have been discussed.
关键词： Bovine leukemia virus (BLV),Photoluminescence,Optical immunosensor,ZnO nanorods,Antigen-antibody complex.
更新于2025-09-23 15:22:29
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Electrical Transport Properties of Thin Film Composed of a-ZnO Nanorods
摘要： Background: Due to its wide band gap, high exciton binding energy and high breakdown strength, the nanostructures of ZnO may find applications for electronic, photonic devices, and high-frequency applications. Objective: The aim of the present work is to study electrical transport of thin film composed of a-ZnO nanorods. Method: Physical vapour condensation method was employed to fabricate the nanorods of ZnO. The morphology of these nanorods was investigated with the help of scanning electron microscope. X-ray diffraction pattern of as-prepared thin film was recorded using X-ray diffractometer. For dc conductivity measurements, four-probe method was used. Result: The as-prepared ZnO nanorods have diameter ranging from 10-20 nm and the length is of order of few hundred nanometers. XRD pattern of film composed of ZnO nanorods suggests the amorphous nature. Temperature dependence of dc conductivity has been studied over the temperature range of (297- 4.2K). For the temperature range of 297-120K, Mott’s three dimensional variable range hopping (VRH) is applied to explain the electrical conduction. For lower temperature range (120 - 4.2K), 2D-variable-range hopping in localized states near the Fermi level may be responsible for the transport of carriers. Conclusion: Variable range hopping mechanism (VRH) has been suggested for the entire temperature range (298-4.2K) on the basis of temperature dependence of dc conductivity data, which changes from 3D to 2D on moving to lower temperatures side (below 125K).
关键词： physical vapour condensation technique,variable range hopping,XRD,ZnO nanorods,SEM,Mott’s parameters,electrical conduction mechanism
更新于2025-09-23 15:22:29
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Graphene oxide coated flower-shaped ZnO nanorods: Optoelectronic properties
摘要： In this paper, the influence of graphene oxide coating on optical and photoluminescence properties of zinc oxide nanorods (ZnO NRs) has been investigated. ZnO NRs were prepared using a hydrothermal route (from zinc nitrate hexahydrate and hexamethylenetetramine), graphene oxide (GO) was fabricated by Hummer's method, while for synthesis of ZnO nanorods:graphene oxide nanocomposite (ZnO NRs:GO) on Si (100) substrate, a facile technique (drop coating) was proposed. The structural, morphological, optical and luminescence properties of the films were investigated using X-ray diffraction (XRD) technique, scanning electron microscopy (SEM), together with Fourier transform infrared (FT-IR), Raman, ultraviolet- visible- near-infrared (UV/VIS/NIR) and photoluminescence (PL) spectroscopies. As revealed by XRD analysis, composites display a hexagonal wurtzite type structure with a (101) preferred grain orientation. The average crystallite sizes decrease from 45 to 40 nm after GO coating. The SEM study confirms successful coating of GO layers on flower-like ZnO nanostructures. The FTIR and Raman analyses validated the hybridization of nanocomposite and the strong interaction between ZnO NRs and GO. The band gap of the ZnO NRs:GO nanocomposite is lower (2.95eV) compared to that of ZnO NRs (3.11 eV), as determined from the analysis of UV absorbance spectra. The ZnO NRs:GO nanocomposite exhibits a broad PL band, from ~450 nm to ~750 nm, with a nearly white-light integrated emission and a chromaticity coordinate of (0.25, 0.34). Gaussian deconvoluted broad PL band exhibits three distinct sub-bands, associated with radiative recombinations in ZnO and GO.
关键词： graphene oxide,optical properties,nanocomposite,ZnO nanorods
更新于2025-09-23 15:21:01
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Solar Cells with High Short Circuit Currents Based on CsPbBr <sub/>3</sub> Perovskite-Modified ZnO Nanorod Composites
摘要： 3-D all-inorganic perovskite solar cells have been built using vertically aligned conductive zinc oxide nanorods as the electron transport layer and optical waveguide. Yttrium doping improved the conductivity and hence the electron transportation of the ZnO achieving a threefold improvement of the solar cell efficiency. The vertically aligned nanorods act as optical waveguides and a scaffold, which improved photoabsorption of the perovskite semiconductor by increasing layer thickness. Our device structure was completed with an exfoliated multilayer graphite back contact for effective hole-extraction. The ZnO was most significantly modified by nanometre scale coatings of TiO2 in order to passivate the surface and reduce charge recombination, as measured by photoluminescence spectroscopy. This led to greatly improved charge transfer. This strategy led to an overall nine times enhancement in the solar cell efficiency, yielding a competitive top value of 5.83%. More importantly, the all-inorganic solar cells demonstrated excellent stability, showing no decline in initial performance after 1000 hour storage in ambient conditions. This work presents yttrium doped ZnO nanorods as a suitable replacement for mesoporous TiO2, achieving a high short circuit current of 10.5 mA cm-2 for CsPbBr3 perovskite devices.
关键词： Graphite,ambient synthesis,Inorganic perovskite,TiO2 coating,ZnO nanorods
更新于2025-09-23 15:21:01
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High performance CsPbBr <sub/>3</sub> quantum dots photodetectors by using zinc oxide nanorods arrays as an electron-transport layer
摘要： The electron transport layer (ETL) in perovskite photodetectors is playing a vital role in highly efficient electron extraction. Herein, this work reports a perovskite photodetector based on hydrothermal-fabricated ZnO nanorods (NRs) as the ETL and hot-injection-fabricated CsPbBr3 quantum dot (QD) as the photoabsorber. The crystalline structure, morphologies, and photoluminescence (PL) of the materials and the physics mechanism of highly efficient electron extraction in the devices are characterized and analyzed. The PL and time-resolved PL confirm the reduced recombination and enhanced electron transport to the indium tin oxide anode. The photodetectors based on ZnO NRs/CsPbBr3 QDs exhibit enormous enhancement in the response parameters such as a rise time of 12 ms, a decay time of 38 ms, and an on/off ratio of 3000, compared with the photodetectors based on ZnO films/CsPbBr3 QDs. These results indicate that the fabricated ZnO NRs/CsPbBr3 QDs heterojunction has a wide prospect of future applications in photodetectors.
关键词： electron transport layer,photoluminescence,ZnO nanorods,perovskite photodetectors,CsPbBr3 quantum dots
更新于2025-09-23 15:19:57
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Fast-Response and Self-Powered Cu <sub/>2</sub> O/ZnO Nanorods Heterojunction UV-Visible (570 nm) Photodetectors
摘要： A fast, self-powered photodetector (PD) capable of UV to visible (570 nm) sensing based on the p-Cu2O/n-ZnO nanorods (NRs) heterostructure is reported. The PD shows a spectral response range from 380 nm to 570 nm, which is suitable for ambient light sensing applications. The PD exhibits good rectifying characteristics with a low leakage current and a low turn-on voltage of ～0.3 V. The responsivities of the self-powered PD are 0.24 A W?1 and 0.06 A W?1 at 380 and 450 nm, respectively. The rise/recovery time of the PD are 0.02/0.03 s and 0.01/0.02 s for UV (370 nm) and visible light (450 nm), respectively. Upon UV light illumination, the long, persistent photocurrent (or recovery time) caused by ZnO NRs can be eliminated using the self-powered mode.
关键词： fast-response,p-Cu2O/n-ZnO nanorods heterostructure,self-powered photodetector,UV-Visible sensing
更新于2025-09-23 15:19:57
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Highly Rectifying Heterojunctions Formed by Annealed ZnO Nanorods on GaN Substrates
摘要： We study the effect of thermal annealing on the electrical properties of the nanoscale p-n heterojunctions based on single n-type ZnO nanorods on p-type GaN substrates. The ZnO nanorods are prepared by chemical bath deposition on both plain GaN substrates and on the substrates locally patterned by focused ion beam lithography. Electrical properties of single nanorod heterojunctions are measured with a nanoprobe in the vacuum chamber of a scanning electron microscope. The focused ion beam lithography provides a uniform nucleation of ZnO, which results in a uniform growth of ZnO nanorods. The specific configuration of the interface between the ZnO nanorods and GaN substrate created by the focused ion beam suppresses the surface leakage current and improves the current-voltage characteristics. Further improvement of the electrical characteristics is achieved by annealing of the structures in nitrogen, which limits the defect-mediated leakage current and increases the carrier injection efficiency.
关键词： chemical bath deposition,nanoscale heterojunctions,ZnO nanorods,nanoprobe in the scanning electron microscope,current-voltage characteristics,annealing,focused ion beam patterning
更新于2025-09-23 15:19:57