How PtOx/CeO2 Nanostructures Catalyze CO Oxidation at Very Low Temperatures

Journal article, 2026

Nanomaterials based on Pt and ceria (CeO2) that are subjected to oxidative pretreatments can catalyze the CO oxidation reaction at temperatures below 0 degrees C, which is relevant for the conversion of low-temperature combustion emissions. However, the mechanisms by which such systems catalyze the low-temperature CO oxidation reaction remain unclear; the apparent activation energies measured experimentally for Pt/CeO2 catalysts active below 0 degrees C are low and inconsistent with the activation barriers calculated using density-functional theory (DFT) on various oxidized or reduced ceria-supported Pt models. This study demonstrates, by means of DFT modeling and kinetic Monte Carlo simulations, CO oxidation pathways on stable ceria-supported PtOx clusters involving activation energies, turnover frequencies, and reaction temperature onsets consistent with low-temperature experimental catalytic data. These reaction pathways involve the oxidation of CO with O atoms of the supported PtOx clusters instead of those from the CeO2 support often suggested for Mars van Krevelen mechanisms on ceria-supported metal catalysts. In contrast to the often-assumed higher reactivity of interface sites, the low-temperature CO oxidation mechanism via top-layer O atoms of the Pt6O9 cluster distant from the support exhibits higher turnover frequencies than the mechanism involving interface O atoms of the cluster. These mechanistic insights pave the way for designing very low-temperature oxidation catalysts based on stable supported metal-oxide clusters.