Efficient electrochemical water oxidation mediated by a binuclear copper complex with a helical structure

Herein, electrochemical water oxidation catalyzed by a binuclear copper complex [Cu 2 (MePy 3 P) 2 ] ( 1 , MePy 3 PH 2 = N , N ′-bis[2-(2-pyridyl)methyl]pyridine-2,6-dicarbox-amide) with a helical structure is reported. Oxygen evolution occurs with a low onset overpotential of 483 mV, high turnover frequency of 18.04 s −1 and moderate faradaic efficiency in neutral phosphate buffer solution, performing better than numerous copper-based homogeneous catalysts. Kinetic tests and electrochemical examinations reveal that complex 1 homogeneously catalyzes water oxidation. The mechanism of electrochemical water oxidation mediated by complex 1 is proposed according to electrochemical test results, which reveals that the two Cu cores of complex 1 undergo nucleophilic attack by water and then take part in the formation of an O-O bond. The outstanding catalytic activity of complex 1 may be attributed to the intramolecular interactions of its two adjacent Cu cores during the catalytic cycle. This work suggests that development of copper complexes with a neighboring multinuclear structure is a feasible strategy to obtain an efficient water oxidation catalyst. A binuclear Cu complex [Cu 2 (MePy 3 P) 2 ] is found to be capable of catalyzing electrochemical water oxidation under neutral conditions via the intramolecular interaction of its two Cu cores, achieving a remarkable turnover frequency of 18.04 s −1 and onset overpotential of 480 mV for oxygen evolution.