Activity Analysis of [(NH3)5RuORu(NH3)5]5+, Confined in a Coated-Polymer Membrane for Electrochemical Water Oxidation

Abstract

The activity of the electrochemical water oxidation catalyst, [(NH3)5RuORu(NH3)5]Cl5, incorporated in an electrode-coated Nafion membrane was studied. The turnover number (TN) of the catalyst increased with the increase, of its concentration in the membrane in low concentration regions because of facilitated charge transfer between the catalysts, while that decreased with the concentration in high concentration regions because of bimolecular decomposition of the catalyst. An activity model for the electrochemical catalyst in a membrane was applied based on intermolecular distance distribution, and the activity was analyzed in terms of a charge transfer distance (r0/nm) and a critical decomposition distance (rd/nm); their values were obtained as 1.14 nm and 1.09 nm, respectively. The, activity was compared with other complexes. It was elucidated that the activity of the catalysts increased with the number of the metal ion present in one molecule.