Nanostructured bismuth vanadate (BiVO4) thin films for efficient visible light photocatalysis

Abstract

Successful strategies on combining the versatility of mechanochemical synthesis with rf-sputtering technique were developed for the controllable deposition of non-toxic and stable monoclinic BiVO4 thin films, which has a relatively narrow band gap (≈2.4 eV) that allows a direct photoactivation under visible light. The coupled deposition approach enables the stabilization of single phase, high-quality monoclinic BiVO4 thin films, deposited using sintered target made with nano-powders produced from mechanochemical process. Investigations of structural, vibrational, morphological and optical properties were carried out using HT-XRD, XRD, Raman, AFM, FE-SEM and UV-Visible absorption techniques. Monoclinic scheelite phase of BiVO4 was studied with different morphologies and textures of thin film surfaces including the occurrence of organized nano-islands (20-50 nm) under defined deposition parameters. The sputtered BiVO4 films display an electronic band gap of 2.5 eV, which is suitable for harvesting visible light radiation. Photocatalytic (PC) experiments were performed with selected textured BiVO4 thin films for the degradation of rhodamine 6G (Rh6G) dyes under visible light irradiation. Different PC efficiencies were obtained and the results were interpreted based on the thin film morphologies and surface characteristics.