Photoreduction of dioxygen to hydrogen peroxide at porphyrins and phthalocyanines adsorbed Nafion membrane

Abstract

The metal porphyrins (MP) and metal phthalocyanines (MPC) adsorbed Nafion membranes are prepared (Nf/MP and Nf/MPC) and used as photocatalysts for the photoreduction of dioxygen (O₂). Photoinduced electron transfer reactions carried out using the MP and MPC adsorbed Nafion membrane. The back electron transfer reaction between h⁺ with O₂^- is prevented by the reaction of the hole with an electron donor triethanolamine (TEA). Hydrogen peroxide (H₂O₂) is produced by the reaction of the semiconducting nature metal porphyrins and phthalocyanines with dissolved dioxygen. The photosensitized reaction mechanism of the photocatalytic reduction of O₂ to H₂O₂ formation is explained. The turnover number of the photocatalysts are high in the presence of sacrificial electron donor. The surface morphology of the modified photocatalysts are analysed by scanning electron microscope. The detailed mechanism of the dioxygen reduction in the modified systems are presented.