Enhanced CO2 photocatalytic reduction through simultaneously accelerated H2 evolution and CO2 hydrogenation in a twin photoreactor

The photocatalytic reduction of CO2 utilizes solar energy to mitigate CO2 emissions and is a promising technology for renewable fuel production. In this study, a novel twin reactor was developed to hydrogenate CO2 into hydrocarbons by using H2 directly produced from photocatalytic water splitting. The twin reactor was further modified to simultaneously perform the CO2 hydrogenation and water splitting reactions in the gas and liquid phases, respectively. Moreover, two photocatalysts, Pt/TiO2 and Cu/TiO2, were used to improve the photo-hydrogenation performance in the reactor. The results indicate that the H2 produced from water splitting effectively enhanced the CO2 hydrogenation in the gas phase, and we found that the highest CO2 reduction activity was achieved by using Pt/TiO2 and Cu/TiO2 as the H2-generating and CO2 hydrogenation photocatalysts, respectively, which promoted H2 evolution and CO2 hydrogenation and resulted in enhanced CO2 photoreduction.