Oxygen evolution by water oxidation with polynuclear ruthenium complexes

Abstract

The electrochemical studies of a trinuclear ruthenium complex (Ruthenium red) have been carried out. Di- and tri-nuclear ruthenium complexes were adsorbed onto clay and ion-exchange resin and were then used as homogeneous and heterogeneous (clay-and resin-adsorbed) catalysts for water oxidation to evolve oxygen. The gas-chromatographic and mass-spectral data clearly show that oxygen evolved by water oxidation is catalysed by the polynuclear ruthenium complexes in the presence of Ce^IV oxidant. The turnover numbers and stabilities of the catalysts were evaluated under various conditions. The observed data show that the trinuclear ruthenium complexes are more efficient towards water oxidation than the dinuclear ruthenium complexes. Based on these results, the four-electron water oxidation process is discussed.