NonCovalent Aggregation‐Driven D‐Band Engineering in Nickel Cocatalysts for Efficient CO 2 Photoreduction

Abstract Efficient CO 2 activation remains a pivotal challenge in photocatalytic CO 2 reduction, necessitating precise electronic modulation of catalytic centers to overcome kinetic limitations. In this work, we engineer Ni(bpy) 3 Br 2 cocatalyst aggregates via noncovalent self‐assembly and systematically unravel the role of aggregation in governing photocatalytic performance. A synergistic combination of experimental and theoretical analyses demonstrates that symmetry disruption within the aggregates induces localized charge redistribution. Such a charge redistribution triggers a 0.6 eV upshift in the Ni d‐band center, which delivers lower Gibbs free energies for the formation of *CO 2 and *COOH. The optimized aggregates achieve a record‐high quantum yield of 26.84% at 450 nm with 99.3% CO selectivity, representing the highest performance reported to date for visible‐light‐driven CO 2 ‐to‐CO conversion systems. Importantly, the d‐band center of the Ni sites can be precisely modulated by varying the aggregation degree of Ni(bpy) 3 Br 2 . This work not only advances a novel d‐band center modulation strategy for electronic configuration engineering but also provides in‐depth atomic‐level insights into the aggregation‐induced symmetry‐regulated d‐band center.