A dinuclear copper(II) electrocatalyst both water reduction and oxidation

Abstract

Splitting water is a key challenge in the production of chemical fuels from electricity. Although several catalysts have been developed for these reactions, substantial challenges remain towards the ultimate goal of an efficient, inexpensive and robust electrocatalyst. Until now, there is as yet no report on both water oxidation and reduction by identical catalyst. Reported here is the first soluble copper-based catalyst, Cu(Me2oxpn)Cu(OH)2] 1 (Me2oxpn: N,N′-bis(2,2′-dimethyl-3-aminopropyl)oxamido) for both electrolytic water oxidation and reduction. Water oxidation occurs at an overpotential of 636 mV vs SHE to give O2 with a turnover frequency (TOF) of ∼2.14 s−1. Electrochemical studies also indicate that 1 is a soluble molecular species, that is among the most rapid homogeneous water reduction catalysts, with a TOF of 654 mol of hydrogen per mole of catalyst per hour at an overpotential of 789 mV vs SHE (pH 7.0). Sustained water reduction catalysis occurs at glassy carbon (GC) to give H2 over a 32 h electrolysis period with 95% Faradaic yield and no observable decomposition of the catalyst.