Base-Enhanced Electrochemical Water Oxidation by a Nickel Complex in Neutral Aqueous Solution

A nickel complex, [Ni(TMC)(CH3CN)](NO3)2 (TMC = 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane, 1), was found to be an efficient water oxidation catalyst in a pH 7 phosphate buffer. It exhibits a pseudo first order kinetics in electrochemical water oxidation with a catalytic rate of 9.95 s-1, the highest rate for nickel WOCs at neutral pH. Complex 1 also show superior catalytic activity with respect to that of copper analogue [Cu(TMC)(H2O)](NO3)2 under the same conditions. Kinetic studies indicate a more than one order rate acceleration with the add bases due to an atom–proton transfer (APT) pathway.