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

The d-band center (ε_d) 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 ε_d 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 ε_d 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 ε_d of catalytic centers without disrupting their covalent framework. This approach enables mild, reversible, and highly tunable ε_d 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.