Porous organic polymer enriched in Re functional units and Lewis base sites for efficient CO2 photoreduction

Abstract

Photocatalytic reduction of CO₂ into valuable chemicals or fuels is one of the most promising solutions to mitigate climate change. However, sound photocatalysts with sensitive responses to light, efficient enrichment and reduction of CO₂ have not been well explored. Herein, we design and synthesize a porous organic polymer (POP), BTN-Re (BTN = 2,2′-bipyridine triazine network) out of two key units, i.e. Re(bpy)(CO)₃Cl (bpy = 2,2′-bipyridine) and melamine. Re(bpy)(CO)₃Cl offers excellent CO₂ reduction ability of functional units to BTN-Re; meanwhile, the abundant Lewis base sites brought in by melamine promote capture of CO₂ contributing to the reduction of CO₂. Steady-state fluorescence tests confirm that integrating Re(bpy)(CO)₃Cl into BTN-Re skeletons efficiently inhibits electron–hole recombination. It is evident that BTN-Re exhibits an outstanding ability to photo-reduce CO₂, with an average rate of 500.7 μmol g⁻¹ h⁻¹ under visible light irradiation. This work provides a novel strategy for designing POP-based materials as photoreduction catalysts to reduce CO₂.