Copper Oxide Cluster Surface Modification-Induced Multiple Electron Oxygen Reduction Reaction on Bismuth Vanadate under Visible-Light Irradiation

Bismuth vanadate (BiVO4) is a promising material for visible-light photocatalysts, but the application is severely limited because the energy of excited electrons is too low to reduce oxygen. In this study, highly dispersed copper oxide clusters were formed on the surface of bismuth vanadate (CuO/BiVO4) by the chemisorption-calcination technique using bis(acetylacetonato)Cu(II) (Cu(acac)2) as a copper source. Electrochemical measurements using rotating electrodes showed that the surface modification gives rise to multiple-electron oxygen reduction reaction under visible-light irradiation. As a result, this robust CuO/BiVO4 stably exhibits a high level of visible-light activity for the degradation of model water pollutant, whereas unmodified BiVO4 is almost inactive. The photocatalytic activity of CuO/BiVO4 strongly depends on the CuO loading amount Γ (ions nm−2) with a sharp increase at Γ ≈ 0.6.