Analysis of cooperative catalysis by a molecular water oxidation catalyst adsorbed onto an inorganic particle matrix

Electrocatalytic water oxidation was carried out using a basal-plane pyrolytic graphite (BPG) electrode coated with electrodeposited Platinum black (Pt-black) adsorbing [Ru(NH 3 ) 5 Cl] 2+ . The amount of O 2 evolved ( V O 2 , mol h −1 ) remarkably increased by adsorbing the complex onto Pt-black. The plots of V O 2 vs. the complex amount on the Pt-black gave a sigmoidal curve, which was explained by both the cooperative catalysis by two molecules of the complex and their bimolecular decomposition. The electrocatalytic activity of the complex was analyzed in terms of its intrinsic activity, k (h −1 ), cooperative catalysis distance, r co (nm) and critical decomposition distance, r d (nm) for both the void space adsorption model (VAM) and surface adsorption model (SAM) based on intermolecular distance distribution. k =940 h −1 , r co =1.21 nm and r d =0.97 nm for VAM and 950 h −1 r co =0.82 nm and r d =0.78 nm for SAM were obtained, respectively. Remarkable high intrinsic activities are ascribed to the efficient charge transfer from the electrode to the complex attached to the Pt-black.