Growth of highly crystalline WO3 nanorod using a facile hydrothermal synthesis

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.