Analysis of Catalytic Water Oxidation by cis-Tetraamminedichlororuthenium(III) Complex Incorporated in a Polymer Membrane

cis-Tetraamminedichlororuthenium(III) (cis-[Ru(NH3)4Cl2]+) complex was found to work as a very active water oxidation catalyst to evolve dioxygen (O2) in an aqueous solution as well as in a Nafion membrane. The initial O2 evolution rate (VO2 (mol s-1)) was first-order with respect to the complex concentration in both the solution and membrane. The catalyst undergoes a bimolecular decomposition to deactivate at high complex concentrations. The first-order rate constant (kO2 (s-1)) for O2 evolution and the second-order rate constant (kdeact (dm3 mol-1 s-1)) for bimolecular decomposition were obtained from the kinetic analysis based on the competition between both processes. The kO2 (1.4 × 10-2 s-1) in the Nafion membrane is much higher than that (2.3 × 10-3 s-1) in the solution. The kdeact (5.1 × 10-1 dm3 mol-1 s-1) in the membrane was slightly higher than that (2.0 × 10-1 dm3 mol-1 s-1) in the solution. The catalytic activity in the Nafion membrane was analyzed in terms of the intrinsic activity (kO2 (s-1)...