Photoelectrocatalytic reactions of metal complexes at chemically modified electrodes

Abstract

One of the outstanding properties of the ion-exchange membranes is their multiphase structure with microheterogeneous environment. Recently we have shown that ion-exchange membranes such as Nafion and clay can be effectively used in preparing chemically modified electrodes with adsorbed photoactive and electroactive molecules. A new photogalvanic cell was constructed by coating one electrode with Nafion-[Ru(bpy)₃]²⁺ and the other with clay-[Ru(bpy)₃]²⁺. This new photogalvanic cell showed an additive photogalvanic response on visible light irradiation. The quenching rate constants,k_q, for the reaction of excited state [Ru(bpy)₃]²⁺ adsorbed into the membrane with Fe³⁺ ion and cobalt(III) complexes were determined by photoelectrochemical methods. The photoelectrocatalytic reduction of oxygen to hydrogen peroxide at chemically modified electrodes was carried out by using [Ru(bpy)₃]²⁺ as sensitizer and macrocyclic cobalt(III) complexes as electron relay.