Single-Cation Catalyst: Ni Cation in Monolayered CuO for COOxidation

It is vital to differentiate catalytic properties between cationic and metallic single atoms at the atomic level. To achievethis, we fabricated well-defined cationic Ni atoms snugged in and metallic Ni atoms supported on monolayered CuO. The Ni cationsare chemically inert for CO adsorption even at 70 K but highly active toward O2dissociation at room temperature. The adsorbed Oatoms are active to oxidize incoming CO molecules from the gas phase into CO2, which follows the Eley-Rideal mechanism, incontrast to the Mars-van Krevelen mechanism on CuO-monolayer-supported metallic Ni atoms as well as our previously reportedAu and Pt model catalysts. This study helps understand the chemistry of a supported single-metal cation, which is of greatimportance in heterogeneous catalysis.