Structural, electronic and optical features of molybdenum-doped bismuth vanadium oxide

Molybdenum (Mo)-doped bismuth vanadium oxide (BiVO4) powders were prepared by a sol-gel method. X-ray diffraction (XRD) patterns and micro-Raman vibrational bands confirm the monoclinic scheelite phase. Molybdenum doping of BiVO4 matrix was confirmed from XRD by higher angle 2 theta shift of the characteristic peak (-121) and from Raman showing lower frequency shift of dominant band from 831 to 822 cm(-1) which corresponds to V-O symmetric stretching mode. EPR investigations confirmed the substitution of Mo in the crystalline sites of monoclinic BiVO4. SEM analysis showed spherical shaped particles around 100-200 nm with weak agglomerated particles. Homogeneous presence of molybdenum in BiVO4 matrix was confirmed from STEM analysis. Diffuse reflectance spectra showed higher absorption in the range of 550-850 nm and optical band gap energies were calculated by using the Kubelka-Munk formula, i.e, 2.46 eV for 2 wt% Mo-BiVO4 and 2.48 eV for undoped BiVO4. This confirms that, Mo-BiVO4 particles have almost the same energy band gap but induce higher absorption in the visible light region as compared to undoped material. (C) 2014 Elsevier Ltd. All rights reserved.