Biomass derived ZnO/N-doped porous carbon for photo-induced CO2 cycloaddition

Accumulation of atmospheric CO2 poses a serious threat to the global environment, but there is still a lack of effective CO2 catalytic conversion under mild conditions. Herein, multifunctional ZnO/N-doped porous carbon materials, ZNPC-X, were fabricated by pyrolysis of available pine pollen with melamine and zinc chloride. The optimized ZNPC-600 produced at 600 °C can work as an efficient photothermal catalyst towards CO2 cycloaddition conversion with a high catalytic yield of 99% under mild conditions (0.3 W/cm2, 1 bar). Moreover, ZNPC-600 shows excellent recyclability after ten cycles and desirable performance even under simulated flue gas and after moisture treatment. Absorption spectra and time-dependent infrared images unveil that the intrinsically broad light absorption and high photothermal conversion efficiency are the major reasons for the high activity of ZNPC-600. Besides, photogenerated electrons can be transferred to CO2 and activate it, while photogenerated holes can be used as Lewis acid to facilitate the ring opening of epoxides. In addition, the hierarchical pore structure and the synergy between ZnO and pyridine N also play a role in the mass transfer and activation of epoxides and CO2, respectively. This work provides a low-cost and facile solution to obtain catalysts derived from biomass for promoting CO2 conversion.