Ultralow-Barrier CO Oxidation on BiOS-Supported Single-Atom Catalysts: Mechanistic Insights and Electronic Descriptors.

Efficient CO oxidation is critical for environmental catalysis. Here, we investigate CO oxidation on single transition metal atoms (TM = Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, and Pt) supported by BiOS using density functional theory and molecular dynamics. The reaction proceeds exclusively via the Eley-Rideal mechanism, except for Pd, with activation barriers ranging from 3.6 to 43.7 kJ/mol. Group 9 (Co, Rh, and Ir) and 10 (Ni and Pt) metals demonstrate superior performance, exhibiting ultralow barriers below 10 kJ/mol. We identify two electronic descriptors: a static descriptor quantifying pre-transition-state O-TM bond stability, which is inversely correlated with activation barriers, and a dynamic descriptor tracking the shift of the occupied orbital center from the pre-transition-state intermediates to transition states, directly linked to barrier heights. BiOS-supported single-atom catalysts enable ultralow-barrier CO oxidation, indicating great potential for environmental applications and providing design principles for efficient single-atom catalysts for CO oxidation.