A Bio-inspired Cu O Cubane: Effective Molecular Catalysts for Electrocatalytic Water Oxidation in Aqueous Solution.

Inspired by the cubic Mn CaO cluster of natural oxygen-evolving complex in Photosystem II, tetrametallic molecular water oxidation catalysts, especially M O cubane-like clusters (M=transition metals), have aroused great interest in developing highly active and robust catalysts for water oxidation. Among these M O clusters, however, copper-based molecular catalysts are poorly understood. Now, bio-inspired Cu O cubanes are presented as effective molecular catalysts for electrocatalytic water oxidation in aqueous solution (pH 12). The exceptional catalytic activity is manifested with a turnover frequency (TOF) of 267 s for [(L -Cu) ] at 1.70 V and 105 s for [(L -Cu) ] at 1.56 V. Electrochemical and spectroscopic study revealed a successive two-electron transfer process in the Cu O cubanes to form high-valent Cu and Cu O intermediates during the catalysis.