Utilization of Fe3+/Fe2+ redox for the photodegradation of organic substances over WO3 photocatalyst and for H2 production from the electrolysis of water

WO3 is a visible-light-responsive photocatalyst, but the potential of its conduction band is not negative enough to produce H-2 from water or to reduce O-2 in the photodegradation reaction of various waste organic materials, environmental pollutants, and biomass. The activity of WO3 for the photodegradation of various organic substances into CO2 was markedly enhanced by the addition of Fe3+, Mainly due to the electron-accepting effect of the reduction of Fe3+ to Fe2+. WO3 in the presence of Fe3+ was more active than TiO2 even under ultraviolet-visible light for the degradation of lower-molecular-weight organic substances. The Fe2+ generated in the photocatalytic reaction could be oxidized to Fe3+ by means of a hybrid system of electrolysis and photocatalysis accompanied by the production of H-2 from water at a low external bias (< 1 V).