D-band center-driven photocatalyst design for CO2 reduction: mechanisms, modulation, and perspectives.

The d-band center (εd) theory is a fundamental electronic descriptor that enables the adsorption behavior of key intermediates in photocatalytic CO2 reduction to be understood and predicted, thereby providing a rational basis for the design of high performance catalysts. This review systematically surveys recent advances in εd driven photocatalyst design, focusing on two distinct yet complementary modulation paradigms: strong chemical interactions and weak noncovalent interactions. Conventional strong-interaction strategies, including strain engineering, ligand effects, alloying, vacancy creation, chemical doping, and heterointerface construction, can induce pronounced and often irreversible εd shifts by modifying atomic spacing, coordination environments, or interfacial charge transfer. However, these approaches generally require harsh conditions and provide limited dynamic tunability. In contrast, weak noncovalent interactions, such as π-π stacking, and van der Waals forces, represent an emerging strategy that induces charge redistribution and effectively upshifts the εd of catalytic centers without disrupting their covalent framework. This approach enables mild, reversible, and highly tunable εd modulation. Finally, we discuss future opportunities, including the synergistic integration of strong and weak interactions, advanced in situ characterization, dynamic regulation, and theory driven high-throughput screening.