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Employing density functional theory, we delved into the comprehensive pathways for methane oxidation on the Pd single atom supported with CeO2(111) encompassing sequential methane dehydrogenation, O2dissociation, and oxidation processes. The introduction of a Pd atom into CeO2(111) led to a reduction in the barrier for CH4dissociation to 0.50 eV. The methane dehydrogenation proceeded through a series of reactions: CH4→ CH3→ CH2→ CH → C, with all dehydrogenation steps being exothermic except the CH3→ CH2step. The O2dissociation reaction (O2→ O* + O*) is thermodynamically exothermic, with a dissociation barrier of 2.12 eV over Pd@CeO2. Subsequently, the generation of CO2via the C* + O* and CO* + O* reactions is characterized by thermodynamically exothermic processes, with reaction energies of −1.20 and −1.01 eV, respectively. On the other hand, water production occurs through O* + H (an exothermic reaction) and OH* + H (an endothermic reaction) with reaction energies of −0.80 and +0.64 eV, respectively. These findings offer valuable insights into the potential pathways for single-atom catalysis involving transition metals supported on CeO2(111) in methane oxidation for industrial application.

This study investigates the catalytic degradation of ground-level ozone on low-index stoichiometric and reduced CeO2surfaces using first-principles calculations. The presence of oxygen vacancies on the surface enhances the interaction between ozone and the catalyst by serving as active sites for adsorption and decomposition. Our results suggest that the {111} surface has superior ozone decomposition performance due to unstable oxygen species resulting from reactions with catalysts. However, when water is present, it competes with ozone molecules for these active sites, resulting a reduced catalytic activity or water poisoning. A possible solution could be heat treatment that reduces the vacancy concentration, thereby increasing the available adsorption sites for ozone molecules while minimizing competitive adsorption by water molecules. These results suggest that controlling moisture content during operation is crucial for the efficient use of CeO2-based catalysts in industrial applications to reduce ground-level ozone pollution.