Structural and optical properties of molybdenum doped bismuth vanadate powders

Molybdenum doped BiVO4 powders were prepared by Sol-gel method. Monoclinic scheelite phase was confirmed from X-ray diffraction (XRD) patterns and micro-Raman vibrational bands. Substitution of molybdenum in crystal sites of BiVO4 was evidenced from XRD by higher angle 2θ shift of the characteristic peak (-121) and from Raman showing lower frequency shift of dominant peak from 831 to 822 cm-1 which corresponds to V-O symmetric stretching mode. The morphological properties were analyzed by FE-SEM which confirmed the formation of homogeneous spherical shaped particles with size around 200-300nm. Optical properties were analyzed by Diffuse Reflectance Spectra which show higher absorption in the range of 550-850nm. Optical band gap energies were calculated by using Kubelka-Munk formula, i.e, 2.46 eV for 2 wt% Mo-BiVO4 and 2.47eV for undoped BiVO4. This confirms that, Mo-BiVO4 particles have the same band gap but induce higher absorption in visible light region compared to BiVO4.