Transferring strongly reducing electrons to bidentate-adsorbed CO₂ for efficient and selective formate photosynthesis

The photocatalytic conversion of carbon dioxide into formate offers substantial economic value; however, it suffers from the inherent efficiency-selectivity trade-offs. Here, we introduce phthalocyanine polymer dots coexposed with defined phthalocyanine nitrogen (N_pc) and phthalocyanine nitrogen-hydrogen (N_pc─H) sites as promising photocatalysts, achieving synergistic enhancement in efficiency and selectivity. N_pc sites act as electron nodes, directing photogenerated electrons from photosensitizers toward carbon dioxide-adsorbed phthalocyanine, boosting the reactive charge density by 6.5-fold. Concurrently, the N_pc─H sites capture carbon dioxide via bidentate adsorption, triggering a carbon-selective protonation pathway for selective formate photosynthesis. Owing to the synergistic advantages, the photocatalyst achieves a record formate production rate of 15.89 millimoles per gram per hour with 98.8% selectivity under natural sunlight and quantum efficiencies exceeding 5% across a broad visible-light spectrum. By clarifying electron migration and proposing a unique carbon-selective protonation reaction mechanism, this work offers transformable guidelines for sustainable solar energy conversion and controllable photocatalytic carbon dioxide reduction.