Photocatalytic reduction of dioxygen by colloidal semiconductors and macrocyclic cobalt(III) complexes in Nafion and cellulose matrices

Abstract

The colloidal semiconductors TiO 2 and CdS are used for the photosensitized reduction of MV 2+ and Co(III) complexes. Photoinduced electron transfer reactions are carried out using the semiconductors in colloidal state, adsorbed and intercalated into Nafion and cellulose matrices. The back electron transfer reaction between h vb +(TiO 2 or CdS) and MV + · or Co(II) complex is prevented by the reaction of the hole with an electron donor triethanolamine (TEA). Hydrogen peroxide (H 2O 2) is produced by the reaction of the photoproduced MV + · or Co(II) complex with dissolved molecular oxygen (O 2). The photosensitized reaction mechanisms of the formation of MV + · and Co(II) complex and the photocatalytic reduction of O 2 to yield H 2O 2 in the semiconductor modified systems are explained.