Metal-free polymer photocatalysts for efficient gas-phase reduction of atmospheric CO2 and simultaneous H2O2 production

Abstract

Solar-driven reduction of CO₂ into hydrocarbon fuels along with the concurrent production of H₂O₂ using semiconductor photocatalysts represents a promising strategy for alleviating global carbon emissions while simultaneously producing useful chemicals. Herein, a series of benzobisthiazole-bridged conjugated microporous polymers are designed, and efficient CO and H₂O₂ coproduction is achieved for the first time via the direct photoreduction of atmospheric CO₂ with saturated water vapor. The abundant N and S atoms in the porous frameworks provide the polymers with high CO₂/N₂ selectivities of 51–67 at 298 K as well as accessible catalytic sites for activating CO₂ and H₂O molecules under light irradiation. Moreover, TPT-BBT bearing a 2,4,6-triphenyl-1,3,5-triazine unit demonstrates the smallest exciton binding energy and enhanced photoinduced charge transfer among the three polymers. Therefore, upon exposure to simulated solar light (100 mW cm⁻²), metal-free TPT-BBT displays superior CO and H₂O₂ yields of up to 361.2 and 552.7 μmol h⁻¹ g⁻¹, respectively, which are substantially higher than those of most photocatalysts reported thus far under similar conditions. These results offer new insights into the design of high-performance polymer photocatalysts for simultaneous gas-phase CO₂ reduction and H₂O₂ production under mild conditions.