Efficient photocatalytic reduction of CO2 by amine-functionalized g-C3N4

Amine-functionalized g-C3N4 shows enhanced CO2 photoreduction performance, due to the improved CO2 adsorption capacity. •Amine-functionalized g-C3N4 is prepared by simple monoethanolamine treatment.•The functionalized g-C3N4 shows enhanced CO2 photoreduction activity.•The enhanced activity is due to the improved CO2 adsorption capacity. Photocatalytic conversion of CO2 into hydrocarbon fuels using semiconductor photocatalysts has attracted great attention, which is considered as a promising approach to resolve the energy shortage and greenhouse effect. In this work, amine-functionalized g-C3N4 was prepared by heating urea at 500°C, with a subsequent functionalization treatment by monoethanolamine solution. The amine-functionalized g-C3N4 exhibits improved photocatalytic performance on CO2 photoreduction, which can be attributed to the enhanced CO2 adsorption capacity. The optimized photocatalyst shows much higher CO2 conversion efficiency as compared to pure g-C3N4 under the same conditions, with a CH4-production rate of 0.34μmolh−1g−1 and CH3OH-production rate of 0.28μmolh−1g−1. This work demonstrates the surface amine functionalization is a successful strategy to improve the CO2 adsorption capacity of g-C3N4 for the enhancement of CO2 photoreduction activity.