Novel direct Z-scheme Cu2V2O7/g-C-3 N-4 for visible light photocatalytic conversion of CO2 into valuable fuels

In this study, Cu2V2O7/g-C3N4 direct Z-scheme system was prepared for visible light photocatalytic conversion of CO2 into valuable fuels. As compared to the single Cu2V2O7 and g-C3N4, the established Cu2V2O7/g-C3N4 exhibited great increases in the CO2 conversion efficiency. When Cu2V2O7 was combined with g-C3N4 to establish a direct Z scheme system, both Cu2V2O7 and g-C3N4, which are narrow band-gap material, could absorb visible light for excitation of electrons from the valence band (VB) to the conduction band (CB). Then, the excited electrons existed in the CB of the Cu2V2O7 could return to holes in the VB of the g-C3N4 to prevent recombination of excited holes and electrons in each materials. Thus, the established direct Z scheme Cu2V2O7/g-C3N4 system produced significant amount of available holes and electrons. Finally, the produced holes and electrons reacted with H2O and CO2 to generate CO, CH4 and O-2. The 50Cu(2)V(2)O(7)/50g-C3N4, which the Cu2V2O7 mole was equal to the g-C3N4 mole, produced enough electrons and protons for selective CO2 conversion into CH4 rather than CO. The generation rates of CH4, CO and O-2 generated from the visible light photocatalytic conversion of CO2 by 50Cu(2)V(2)O(7)/50g-CN4 were 305, 166 and 706 (mu mol g(-1) cat h(-1)), respectively.