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

Abstract

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 μmol 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.