Multi-Electron-Transfer Catalysts Needed for Artificial Photosynthesis

Abstract

We report a study on catalytic water oxidation by cobalt in oxygen ligand environments because such systems are as promising as any in the water oxidation component of solar fuel production. We have re-examined the catalytic activity of Co(II) in aqueous solution using either [Ru(bpy)3]3+ as a stoichiometric oxidant or in visible-light-driven reactions with persulfate as a sacrificial electron acceptor. In both systems a distinctive induction period is observed. A simple kinetic model is proposed that describes the experimental data well. The presence of an induction period is explained by relatively slow formation of the true catalyst from aquacobalt(II).