Ni Single Atoms/Nanoparticles-Decided Spatial Adjustment of Photocatalytic Redox Sites Boosting CO2 Reduction in H2O Vapour.

Abstract

The kinetics matching of CO2 reduction and H2O oxidation is required in sacrificial agent-free photocatalytic CO2 reduction. It indicates that the modification engineering on photocatalytic H2O oxidation half-reaction except that on photocatalytic CO2 reduction half-reaction should be equally paid attention, which has been easily ignored in most of the literatures. Herein, Ni single atoms (NiSAs) and nanoparticles (NiNPs) co-loaded Ti-MOF-derived TiO2 having a  flower-like nanosphere microstructure (NiSAs@NPs/TC) was developed for synchronous design of well-defined redox active sites of photocatalytic CO2 reduction and H2O oxidation. It was verified that NiNPs and NiSAs as the active sites of CO2 reduction and H2O oxidation, respectively, synergically accelerated photocatalytic redox reactions and enhanced separation of photo-generated carriers. NiSAs@NPs/TC showed a remarkable photocatalytic CO2-reduction performance (CO and CH4 products: 35.60 and 3.41 μmol g-1 h-1, respectively) in H2O vapour which was at the advanced level in published relevant studies. Furthermore, the reaction process of CO2 reduction on NiNPs was proposed based on the key intermediates capture of CO and CH4 production in photocatalytic CO2 reduction by in situ analysis.