Photocatalytic CO reduction using La-Ni bimetallic sites within a covalent organic framework.

The precise construction of photocatalysts with diatomic sites that simultaneously foster light absorption and catalytic activity is a formidable challenge, as both processes follow distinct pathways. Herein, an electrostatically driven self-assembly approach is used, where phenanthroline is used to synthesize bifunctional LaNi sites within covalent organic framework. The La and Ni site acts as optically and catalytically active center for photocarriers generation and highly selective CO-to-CO reduction, respectively. Theory calculations and in-situ characterization reveal the directional charge transfer between La-Ni double-atomic sites, leading to decreased reaction energy barriers of *COOH intermediate and enhanced CO-to-CO conversion. As a result, without any additional photosensitizers, a 15.2 times enhancement of the CO reduction rate (605.8 μmol·g·h) over that of a benchmark covalent organic framework colloid (39.9 μmol·g·h) and improved CO selectivity (98.2%) are achieved. This work presents a potential strategy for integrating optically and catalytically active centers to enhance photocatalytic CO reduction.