Heterobimetallic NiFe Complex for Photocatalytic CO₂ Reduction: United Efforts of NiFe Dual Sites

Catalytic CO₂ reduction poses a significant challenge for the conversion of CO₂ into chemicals and fuels. Ni-Fe carbon monoxide dehydrogenase ([NiFe]-CODH) effectively mediates the reversible conversion of CO₂ and CO at a nearly thermodynamic equilibrium potential, highlighting the heterobimetallic cooperation for the design of CO₂ reduction catalysts. However, numerous NiFe biomimetic model complexes have realized little success in CO₂ reduction catalysis, which underscores the crucial role of precise bimetallic configuration and functionality. Herein, we presented a heterobimetallic NiFe complex for the photocatalytic reduction of CO₂ to CO, demonstrating significantly enhanced catalytic performance compared to the homonuclear NiNi catalyst. Photocatalytic and mechanistic investigations revealed that with the assistance of a redox-active phenanthroline ligand, <b>NiFe</b> achieves dual-site activation of CO₂ through a pivotal intermediate, Ni^II(μ-CO₂^2--κC:κO)Fe^II, where the Lewis acidity of the Fe^II site plays an important role, as corroborated in the homonuclear FeFe system. This study introduces the first heteronuclear NiFe molecular catalyst capable of efficiently catalyzing the reduction of CO₂ to CO, deepening insights into heterobimetallic cooperation and offering a novel strategy for designing highly active and selective CO₂ reduction catalysts.