Non‐Covalent Aggregation‐Driven d‐Band Engineering in Nickel Cocatalysts for Efficient CO2 Photoreduction

Efficient CO2 activation remains a pivotal challenge in photocatalytic CO2 reduction, necessitating precise electronic modulation of catalytic centers to overcome kinetic limitations. In this work, we engineer Ni(bpy)3Br2 cocatalyst aggregates via non‐covalent 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 *CO2 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 CO2‐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)3Br2. 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.