Structural and optical characterization of ball-milled copper-doped bismuth vanadium oxide (BiVO4)

Copper-doped BiVO4 nanoparticles were synthesized by a mechano-chemical method under optimized conditions to obtain a monoclinic scheelite structure. The crystal structure and its evolution with doping were investigated by X-ray powder diffraction, micro-Raman spectroscopy, field emission scanning electron microscopy (FE-SEM) and high-resolution transmission electron microscopy (HRTEM). Spherical shape particles with sizes ranging between 40 and 160 nm, which possess a monoclinic scheelite structure, were obtained. From the structural data analysis, it can be observed that the particle size decreases and distortions occur as the copper content increases in doped BiVO4. Chemical bonding and valence states of the Bi-4f, V-2p, O-1s and Cu-2p ions were investigated by XPS which revealed the location of Cu ions in the host lattice of BiVO4 in agreement with EPR investigations. UV-visible absorption experiments showed a broad band in the visible range with a small shift of the energy band-gap from 2.41 eV for undoped BiVO4 to 2.34 eV for 10 at.% Cu-BiVO4. Additional absorption band shoulders and widening of the optical absorption spectrum in the visible range with a well crystalline monoclinic scheelite structure pave the way for efficient visible light-driven photocatalytic activity. Photocatalytic measurements reprinted in supplementary data.