Rapid synthesis of novel Cr-doped WO3 nanorods: an efficient electrochemical and photocatalytic performance

Novel Cr-doped WO 3 nanorods were successfully synthesized by a facile one-step microwave irradiation method for the first time without using any surfactants. The role of Cr on structural, morphological and optical properties was systematically analyzed by using powder X-ray diffraction (PXRD), Raman spectra, electron paramagnetic resonance, scanning electron microscope (SEM), transmission electron microscopy (TEM), UV–Vis diffusion reflectance spectra (DRS) and photoluminescence spectra analysis. XRD analyses confirm that both pure and Cr-doped WO 3 were monoclinic structure of nanocrystalline WO 3 , whereas the SEM and TEM images exhibit spherical and nanorods-like morphology of the as-synthesized pure and Cr-doped WO 3 , respectively. The diameter and length of the nanorods are found to be 55–65 and 140–160 nm, respectively. A noticeable red shift in the absorbance edge and decreasing the band gap from 3.01 to 2.72 eV for Cr-doped samples were observed by using UV–DRS analysis. The electrochemical properties were significantly improved by Cr-doped WO 3 ; this might be due to high surface area that facilitates the contact and transport of electrolyte, providing longer electron pathways and therefore giving rise to highest capacitance in nanorods morphology. The samples were further evaluated by the degradation of methylene blue under visible light irradiation. The photocatalytic activity and reusability of Cr 10 sample were much higher than that of the pure WO 3 . The improvement mechanism by Cr doping was also discussed.