Isolated cobalt ions on nitrogen-doped carbon (Co−N−C) catalyze CO oxidation at temperatures as low as 196 K, but the active site and mechanism for this reaction remain elusive. In this work, steady-state CO oxidation around 273 K over Co−N−C revealed nearly first-order behavior in both CO and O 2 as well as a negative apparent activation energy. Isotopic transient analysis of the reaction confirmed a rapid turnover frequency and low surface coverage of adsorbed intermediates leading to CO 2 (<10% of the Co). Results from kinetics experiments combined with quantum chemical calculations and molecular dynamics simulations are consistent with a reaction path involving weak adsorption of CO onto Co ions followed by a low barrier for the CO-assisted activation of weakly adsorbed O 2 . This proposed mechanism for dioxygen activation does not involve a redox cycle with the transition-metal ion and may be important in other low-temperature catalytic reactions involving O 2 .

Binding strength between cation and anion in a ligand has a major impact on their charge trap passivation efficacy.