Molecular modulation of nickel-salophen organic frameworks enables the selective photoreduction of CO₂ at varying concentrations

Photocatalytic CO2 reduction to value-added chemicals is appealing but challenging, especially under dilute CO2 conditions. Herein, we present a molecular modulation strategy for porous metal-salophen organic frameworks (M-SOFs), involving cooperative regulation of the catalytically active metal centers and their local coordination environments for selective photocatalytic CO2 reduction across a wide range of CO2 concentrations. The optimal Ni-SOF shows a remarkable photocatalytic CO production rate of 16 908 mu mol h(-1) g(-1) and near-unity selectivity under a pure CO2 atmosphere, along with excellent structural stability. More impressively, it largely preserves the catalytic activity and selectivity even when exposed to dilute CO2 (5-20 vol%). Both experimental and theoretical analyses support that the specific Ni-N2O2 coordination environment in the Ni-SOF endows it with strong CO2 binding capacity. This, coupled with nanoporous skeletons, enhances local CO2 enrichment and facilitates its subsequent conversion at the catalytic centers, thereby leading to superior photocatalytic performances at various CO2 concentrations.