Understanding oxygen transfer on ceria with Pt single atoms for surface reaction

Reducible metal oxides are widely used in surface reactions, primarily due to their ability to activate and transfer oxygen. Ceria, known for its rapid Ce³⁺/Ce⁴⁺ redox property, is well-known to follow Mars van Krevelen mechanism. In this study, we prepare Pt/CeO₂-Al₂O₃ catalysts with different ceria domain sizes of 3.7, 5.6, and 7.3 nm to understand oxygen transfer, mainly O₂ activation and lattice oxygen transfer. The ceria domains are isolated on the alumina, preventing oxygen transfer between the ceria. Pt single atomic structures are meticulously prepared to exclude O₂ activation on Pt nanoparticles and provide uniform active sites. Interestingly, the activity trend for CO oxidation is reversed in O₂-rich and O₂-deficient conditions. O₂ activation occurs efficiently in small ceria domains of 3.7 nm. In contrast, larger ceria domains exhibit less O₂ activation but significant lattice oxygen transfer. This behavior is also modeled using large-scale molecular dynamics simulations with a neural network potential trained on first-principles data. Based on these understanding, the catalyst for methane oxidation is proposed by accelerating O₂ activation in O₂-rich condition. This work provides an impactful platform for understanding metal oxide catalysts.