The Reduced Barrier for the Photogenerated Charge Migration on Covalent Triazine-Based Frameworks for Boosting Photocatalytic CO2 Reduction Into Syngas

Abstract

Photocatalytic CO₂ reduction together with hydrogen generation is a promising approach to generate syngas, the photogenerated electron migration from photosensitizers to the catalytic active sites is the rate-determining step. Herein, an integrative strategy is presented by covalently grafting metal complexes into donor–acceptor covalent triazine-based frameworks. The catalytic active sites are integrated with the photosensitizer units by covalent linkages to form an extended π-conjugated framework, which significantly reduces the energy barrier for the migration of the photogenerated charge carriers, resulting in high activity and durability in photocatalytic CO₂ reduction into syngas under visible light irradiation. The CO and H₂ evolution amounts in 1.5 h are 1086 and 1042 µmol g⁻¹, respectively, which greatly surpass those in the host-guest counterparts. Furthermore, selective adsorption for CO₂ over N₂ renders this photocatalytic system to be effective for syngas production from the simulated flue gas. This study provides new approaches to construct the integrative photocatalytic systems for solar-to-chemical energy conversion.