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

Artikel i vetenskaplig tidskrift, 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.