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

The kinetics matching of CO reduction and HO oxidation is required in sacrificial agent-free photocatalytic CO reduction. It indicates that the modification engineering on photocatalytic HO oxidation half-reaction except that on photocatalytic CO 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 TiO having a flower-like nanosphere microstructure (NiSAs@NPs/TC) was developed for synchronous design of well-defined redox active sites of photocatalytic CO reduction and HO oxidation. It was verified that NiNPs and NiSAs as the active sites of CO reduction and HO oxidation, respectively, synergically accelerated photocatalytic redox reactions and enhanced separation of photo-generated carriers. NiSAs@NPs/TC showed a remarkable photocatalytic CO-reduction performance (CO and CH products: 35.60 and 3.41 μmol g h, respectively) in HO vapour which was at the advanced level in published relevant studies. Furthermore, the reaction process of CO reduction on NiNPs was proposed based on the key intermediates capture of CO and CH production in photocatalytic CO reduction by in situ analysis.