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

Catalyst design for the efficient CO 2 reduction reaction (CO 2 RR) remains a crucial challenge for the conversion of CO 2 to fuels. Natural Ni-Fe carbon monoxide dehydrogenase (NiFe-CODH) achieves reversible conversion of CO 2 and CO at nearly thermodynamic equilibrium potential, which provides a template for developing CO 2 RR catalysts. However, compared with the natural enzyme, most biomimetic synthetic Ni-Fe complexes exhibit negligible CO 2 RR catalytic activities, which emphasizes the significance of effective bimetallic cooperation for CO 2 activation. Enlightened by bimetallic synergy, we herein report a dinickel complex, Ni II Ni II (bphpp)(AcO) 2 (where NiNi(bphpp) is derived from H 2 bphpp = 2,9-bis(5- tert -butyl-2-hydroxy-3-pyridylphenyl)-1,10-phenanthroline) for electrocatalytic reduction of CO 2 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 [Fe 3 S 4 ] 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 2 reduction catalysis and provides valuable guidance for the rational design of CO 2 RR catalysts.