Bifunctional integration of La-Ni diatomic sites with optical and catalytical activity for efficient CO2 photoreduction

Abstract Dual-atom catalysts possess a significant potential for promoting CO2 photoreduction to lucrative solar fuels. However, the precise construction of the diatomic sites that simultaneously foster light absorption and catalytic activity is a formidable challenge, as both processes follow distinct pathways in the photocatalyst. Herein, a facile electrostatic-driven self-assembling approach is employed to realize a bifunctional architecture of a diatomic LaNi-Phen (Phenanthroline)/covalent organic framework (COF-5) photocatalyst. The La site acts as an optically active center for the photoinduced generation of carriers, while the Ni site serves as the catalytically active center for highly selective CO2-to-CO reduction enabled by directional charge transfer via COF-5. Density functional theory (DFT) calculations and in-situ characterization reveal the efficient synergistic effect of the La-Ni double-atomic sites, leading to decreased reaction energy barriers of *COOH intermediate and enhanced CO2-to-CO conversion. As a result, in the absence of any additional photosensitizers, a 15.2 times enhancement of the CO2 reduction rate (605.8 µmol·g− 1·h− 1) over that of pristine COF-5 colloid (39.9 µmol·g− 1·h− 1) and an improvement in CO selectivity to 98.2% are achieved. This work presents a novel strategy for integrating optically and catalytically active centers, which results in a diatomic synergy effect enabling high-performance photocatalytic CO2 reduction.