Generation of OH radicals and oxidation mechanism in photocatalysis of WO3 and BiVO4 powders

WO3 and BiVO4 attract widely research interests for their ability to oxidize water and generate O-2 by visible light. In order to clarify the photocatalytic oxidation mechanism, OH radical ((OH)-O-center dot) generation in the photocatalytic reactions was investigated by a fluorescence probe method under 470 nm LED irradiation using coumarin and coumarin-3-carboxylic acid as fluorescence probes. The generation yield of (OH)-O-center dot for WO3 was found to be comparable to that for anatase TiO2, while that for BiVO4 was much smaller. On Cu2+ deposition, the (OH)-O-center dot generation rate was increased for BiVO4, but not for WO3. On the addition of H2O2, the yield of (OH)-O-center dot was increased for all the photocatalysts used. On the basis of the results the difference in the oxidation mechanism in WO3 and BiVO4 photocatalysis was discussed. (C) 2015 Elsevier B.V. All rights reserved.