Electrocatalytic CO2 Reduction and H2 Evolution by a Copper (II) Complex with Redox-Active Ligand

The process of electrocatalytic CO2 reduction and H-2 evolution from water, regarding renewable energy, has become one of the global solutions to problems related to energy consumption and environmental degradation. In order to promote the electrocatalytic reactivity, the study of the role of ligands in catalysis has attracted more and more attention. Herein, we have developed a copper (II) complex with redox-active ligand [Cu(L-1)(2)NO3]NO3 (1, L-1 = 2-(6-methoxypyridin-2-yl)-6-nitro-1h-benzo [D] imidazole). X-ray crystallography reveals that the Cu ion in cation of complex 1 is coordinated by two redox ligands L-1 and one labile nitrate ligand, which could assist the metal center for catalysis. The longer Cu-O bond between the metal center and the labile nitrate ligand would break to provide an open coordination site for the binding of the substrate during the catalytic process. The electrocatalytic investigation combined with DFT calculations demonstrate that the copper (II) complex could homogeneously catalyze CO2 reduction towards CO and H-2 evolution, and this could occur with great performance due to the cooperative effect between the central Cu (II) ion and the redox- active ligand L-1. Further, we discovered that the added proton source H2O and TsOH center dot H2O (p-Toluenesulfonic acid) could greatly enhance its electrocatalytic activity for CO2 reduction and H-2 evolution, respectively.

Automated summary

The process of electrocatalytic CO2 reduction and H-2 evolution from water has become a global solution to energy consumption and environmental degradation. The role of ligands in catalysis has been studied to promote electrocatalytic reactivity. In this study, a copper (II) complex with redox-active ligand was developed, which showed great performance in CO2 reduction and H-2 evolution due to the cooperative effect between the central Cu (II) ion and the ligand. Moreover, the addition of a proton source greatly enhanced the electrocatalytic activity.