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

Abstract

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.