Identification of Active Area as Active Center for CO Oxidation over Single Au Atom Catalyst

Identifying the activity origin of noble-metal-based catalysts is extremely important for fundamental research and practical application. We report that single Au atoms on Co3O4 (Au1/Co3O4 single-atom catalysts (SAC)) exhibit excellent activity and stability for CO oxidation and that the activity origin of Au1/Co3O4 SAC is an active area centered by Au1 atom with one nearby Co and O atoms (and/or O vacancy). The turnover frequency is 3.1 s-1 at -75 °C, to our knowledge, which makes Au1/Co3O4 SAC one of the most active Au catalysts for CO oxidation. The activity can be maintained after 10 cycles of temperature-programmed reaction from -100 to 300 °C or storage in air for 1 year, indicating the high stability of Au1/Co3O4 SAC. The isotope, in situ DRIFTS, kinetics, and density functional theory (DFT) results further demonstrate that CO2 is produced through two reaction pathways, following the Langmuir-Hinshelwood (predominant) and Mars-van Krevelen mechanisms, respectively. The present findings pave the way for better understanding supported metal catalysts.