Ultralow-Barrier CO Oxidation on Bi2O2S‑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 (TM1 = Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, and Pt) supported by Bi2O2S using density functional theory and ab initio 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–TM1 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. Bi2O2S-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.