Electrocatalytic Water Oxidation by a Copper(II) Complex of an Oxidation-Resistant Ligand

The copper(II) complex Cu(pyalk)2 (pyalk = 2-pyridyl-2-propanoate) is a robust homogeneous water-oxidation electrocatalyst under basic conditions (pH > 10.4). Water oxidation occurs at a relatively low overpotential for copper of 520–580 mV with a turnover frequency of ∼0.7 s–1. Controlled potential electrolysis experiments over 12 h at 1.1 V vs NHE resulted in the formation of >30 catalytic turnovers of O2 with only ∼20% catalyst degradation. The robustness of the catalyst under fairly harsh conditions and the low overpotential further highlight the oxidation resistance and strong donor character of pyalk.