Dioxygen-enhanced CO2 photoreduction on TiO2 supported Cu single-atom sites

Supported Cu single-atom (Cu-SA) catalysts have exhibited unique activity and selectivity in CO 2 reduction, but they generally suffer from the easy transformation of active Cu δ+ into inactive Cu 0 . Herein, porous TiO 2 supported Cu single atoms (Cu-SAs/TiO 2 ) photocatalyst was fabricated and dioxygen (O 2 ) enhanced photocatalytic CO 2 reduction performance of Cu-SAs/TiO 2 was investigated by in-situ characterizations and theoretical calculations. The results showed that both activity and stability of Cu-SAs/TiO 2 photocatalyst could be improved by feeding a small amount of O 2 (117.6 ppm) in the reaction system. The competitive electron transfer to O 2 on Cu-SAs/TiO 2 maintained dynamic stability of Cu δ+ active sites, and O 2 -derived *OOH species lowered the formation energy barrier of key intermediate *COOH as well as delivered *H species for accelerating intermediates protonation process. Total yield rate of CH 4 and CO reached 34.64 μmol·g cat ·h −1 for CO 2 photoreduction over Cu-SAs/TiO 2 after introducing 117.6 ppm O 2 , accompanied by enhanced durability.