Structural and optical properties of molybdenum doped bismuth vanadate powders

Abstract

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 BiVO 4 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-BiVO 4 and 2.47eV for undoped BiVO 4 . This confirms that, Mo-BiVO 4 particles have the same band gap but induce higher absorption in visible light region compared to BiVO 4 .