Ultralow-Barrier CO Oxidation on Bi₂O₂S-Supported Single-Atom Catalysts: Mechanistic Insights and Electronic...

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.