Vanadium disulfide (VS2), which belongs to transition metal dichalcogenides (TMDs) group, is a prominent material for energy storage application. On the other hand, graphene like carbon-based nanomaterials offer improved electrochemical performance due to high specific surface area, excellent conductivity, good chemical, and mechanical stability. Therefore, composite of graphene like material with TMD have shown better electrochemical performance till date. In this work, we have synthesized VS2/N-rGO composite material, which can be applicable for energy storage device. At first, we have synthesized graphene oxide (GO) using Tour method. Then we reduced GO along with nitrogen doping using hydrothermal route. After that, we have synthesized VS2/N-rGO by hydrothermal method. The X-ray diffraction (XRD) spectrum of GO shows a prominent peak at 10.2°, which implies the interlayer spacing in GO of 8.7 Å. After reduction and doping with nitrogen (N), two peaks are obtained at 24.7° (d = 3.6 Å), and 42.3° (d = 2.1 Å) in the XRD pattern which corresponds to N-rGO. RAMAN spectrum of composite shows the characteristics peaks of VS2 at 141.6, 194.5, 286.4, 404.1, 680.1 and 997.2 cm-1 along with D and G bands coming from the N-rGO. We have also performed the Fourier-transform infrared-spectroscopy (FTIR) and Field-emission gun-scanning electron-microscopy (FEG-SEM) characterizations to investigate the bonding vibration and surface morphology of the materials. The synthesized material is suitable for energy storage applications.
Tungsten oxide (WO3), which is also known as tungsten trioxide and wide band gap semiconductor material has drawn enormous attention among researchers due to its fascinating properties. Using facile one step hydrothermal method, the synthesis and characterizations of highly crystalline 1D nanorod of WO3 are presented in this paper with large scale production of the material. Several characterization techniques, such as transmission electron microscopy (TEM), field emission gun-scanning electron microscopy (FEG-SEM), X-ray diffraction (XRD), UV-vis spectroscopy have been employed to check the crystallinity, surface morphology, shape, and band gap of the nanomaterial. The XRD data confirms about the highly crystalline hexagonal phase of WO3, which agrees well with the JCPDS card no – 01-085- 2459. Nanorod like morphology can be seen in the low-resolution TEM image. In the HRTEM image, the highly crystalline nature of the material is clearly visible and the obtained interplanar spacing is 0.38 nm which matches with the interplanar spacing of (002) plane. The FEG-SEM image shows the 1D nanorod morphology of the synthesized material. The diameters of the nanorods are in the range of 50-300 nm. The Fourier transform infrared spectroscopy (FTIR) revels the structural information about the synthesized material. The broad peak around 805 cm-1 is attributed to the W-O-W bond stretching vibration. Two other peaks appeared at 1405 and 1628 cm-1 are representing the vibration mode of W-OH bond. We have also studied the UV-vis absorption spectroscopy of the WO3 nanorod to investigate the light absorption property of the material. The band gap obtained from the Tauc plot is 3.16 eV, indicates the wide and direct band gap formation of WO3 nanorod. The synthesized material is suitable for various applications, such as gas sensing, UV photodetector, supercapacitor, and photocatalyst.
ZnO is a fascinating wide gap (3.37 eV) semiconductor due to its tunable optical and electrical properties, which can be utilized for several nanodevices such as nanogenerators, photodetectors, sensors, lasers, and TFTs. In this study, we have investigated the effect of the incorporation of dopants on the native defects and corresponding optical properties of ZnO. We have prepared three samples for the current study and such samples are named samples Z-0, Z-1, and Z-2 for undoped ZnO film, undoped ZnO film annealed at 800°C, and phosphorus doped ZnO film by using spin-on dopant method at an elevated temperature of 800°C, respectively. The XRD results show a dominant peak along the (002) plane for all samples. The room-temperature photoluminescence spectra reveal that the broad peak around 542 nm for sample Z-0 gradually shifts towards the UV region for samples Z-1 and Z-2 and appears around 509 nm and 413 nm, respectively. Significantly, such blue emission is associated with the transitions from oxygen vacancies to valence band or zinc interstitial to valance band. Also, relatively huge reductions in oxygen vacancies are observed in phosphorus doped ZnO films as compared with undoped and undoped-anneal films. Further, we have verified such reductions in oxygen vacancies with XPS O-1s spectra-related peaks (~531-532 eV) with high-temperature annealing and phosphorus doping. Therefore, such a type of oxygen vacancy reduction in ZnO films by cost-effective SOD doping technique is highly essential for developing several ZnO-based functional devices.
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