Visible-light-driven copper acetylacetonate decomposition by BiVO4.

Visible-light irradiation to monoclinic scheelite BiVO(4) (m-BiVO(4)) in a solution of copper acetylacetonate (Cu(acac)(2)) has led to its decomposition and Cu recovery. The photonic efficiency at λ = 440 ± 15 nm reaches 3.4%, exceeding the value for the TiO(2)-photocatalyzed reaction at λ = 355 ± 23 nm (2.0%). The adsorption isotherm and the light intensity-dependence of the decomposition rate indicate high adsorptivity of m-BiVO(4) for Cu(acac)(2) or its sufficient supply to the surface reaction sites, which mainly contributes to the high photocatalytic activity. Electrochemical measurements using cyclic voltammetry suggest that the reaction proceeds via the oxidative degradation of the ligand followed by the reduction of the resulting Cu(2+) ions. Under aerobic conditions, the Cu(2+) ions mediate the electron transfer from the conduction band of m-BiVO(4) to O(2) to complete the catalytic cycle.