Control of charge transfer direction by spatial engineering of redox active centers for boosting photocatalytic CO2 reduction

Abstract

Photocatalytic CO2 reduction with H2O to value-added fuels is an advanced strategy to solve the energy crisis and realize carbon neutralization. Herein, the spatial engineering of redox-active sites on different facets of TiO2 was achieved by stepwise selective photo-deposition, which controls the transfer direction of photogenerated electrons and holes. The 2Cu/TiO2/2Co3O4 sample exhibited high photocatalytic CO2 reduction performance with the production of CO, CH4, CH3CH3, and CH2CH2 reached 9.41, 43.52, 5.39, and 1.41 μmol∙gcat-1∙h-1, respectively. Notably, the C2 products was generated over the 2Cu/TiO2/2Co3O4 composite in comparison with pure TiO2 under same reaction condition. The in-situ DRIFTS spectra identify the formation of critical intermediates (*CHO, *CH4, and CHO*CHO*) and reveal the reaction kinetics of H2O oxidation. Moreover, the DFT calculations combined with the in-situ spectral technique are applied to investigate the reaction pathways of photocatalytic CO2 reduction and C–C coupling. This work demonstrated that the spatial engineering of Cu and Co3O4 on TiO2 provides appropriate redox reaction sites to synergistically boost the photocatalytic CO2 reduction and C–C coupling.