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.