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.