Bioinspired Binickel Catalyst for Carbon Dioxide Reduction: The Importance of Metal-ligand Cooperation.

Catalyst design for the efficient CO reduction reaction (CORR) remains a crucial challenge for the conversion of CO to fuels. Natural Ni-Fe carbon monoxide dehydrogenase (NiFe-CODH) achieves reversible conversion of CO and CO at nearly thermodynamic equilibrium potential, which provides a template for developing CORR catalysts. However, compared with the natural enzyme, most biomimetic synthetic Ni-Fe complexes exhibit negligible CORR catalytic activities, which emphasizes the significance of effective bimetallic cooperation for CO activation. Enlightened by bimetallic synergy, we herein report a dinickel complex, NiNi(bphpp)(AcO) (where is derived from Hbphpp = 2,9-bis(5--butyl-2-hydroxy-3-pyridylphenyl)-1,10-phenanthroline) for electrocatalytic reduction of CO to CO, which exhibits a remarkable reactivity approximately 5 times higher than that of the mononuclear Ni catalyst. Electrochemical and computational studies have revealed that the redox-active phenanthroline moiety effectively modulates the electron injection and transfer akin to the [FeS] cluster in NiFe-CODH, and the secondary Ni site facilitates the C-O bond activation and cleavage through electron mediation and Lewis acid characteristics. Our work underscores the significant role of bimetallic cooperation in CO reduction catalysis and provides valuable guidance for the rational design of CORR catalysts.