RESUMO
Inspired by the cubic Mn4 CaO5 cluster of natural oxygen-evolving complex in Photosystem II, tetrametallic molecular water oxidation catalysts, especially M4 O4 cubane-like clusters (M=transition metals), have aroused great interest in developing highly active and robust catalysts for water oxidation. Among these M4 O4 clusters, however, copper-based molecular catalysts are poorly understood. Now, bio-inspired Cu4 O4 cubanes are presented as effective molecular catalysts for electrocatalytic water oxidation in aqueous solution (pHâ 12). The exceptional catalytic activity is manifested with a turnover frequency (TOF) of 267â s-1 for [(LGly -Cu)4 ] at 1.70â V and 105â s-1 for [(LGlu -Cu)4 ] at 1.56â V. Electrochemical and spectroscopic study revealed a successive two-electron transfer process in the Cu4 O4 cubanes to form high-valent CuIII and CuIII O. intermediates during the catalysis.