A mononuclear copper complex as bifunctional electrocatalyst for CO2 reduction and water oxidation

Abstract To mimic natural photosynthesis, it is still a great challenge to couple catalytic CO2 reduction and water oxidation in one single system with high activity. In this work, we have successfully synthesized and characterized a tetra-coordinated mononuclear copper complex [CuIIL2](ClO4)2·2CH3OH (1) (L = methoxy-di-pyridin-2-yl-methanol) with planar configuration, which can simultaneously serve as an efficient molecular electrocatalyst for CO2 reduction and water oxidation. The copper complex displayed electrochemical activity for the reduction of CO2 to CO in DMF solution with the Faraday efficiency (FE) reached ∼85% and a turnover frequency (TOF) of 2.99 s-1 in the presence of proton donor water. Meanwhile, it also can perform electrocatalytic water oxidation with the FE of ∼86% and a high TOF of 9.20 s-1 at the pH of 11.84. The high electrochemical activity of complex 1 for the reduction of CO2 and water oxidation may due to the hydroxyl group on the methoxy-di-pyridin-2-yl-methanol ligand. It represents the first copper complex as homogeneously bifunctional electrocatalyst for CO2 reduction and water oxidation.