Unravelling the Effect of Oxygen on the Sintering Mechanism of Pt/CeO2 in the CO Oxidation Reaction

Abstract

Sintering significantly contributes to the deactivation of supported metal catalysts under reaction conditions, influenced by various factors, including temperature, atmosphere, and metal–support interactions. The sintering mechanism under the reaction conditions remains complex and ambiguous. This study delves into the sintering behavior of platinum on CeO₂ under CO oxidation conditions, mainly employing transmission electron microscopy to elucidate the effects of different gas components on the sintering mechanism at elevated temperatures. An atmosphere rich in oxygen promotes the sintering of Pt via the Ostwald ripening mechanism, characterized by the growth of larger nanoparticles at the expense of smaller ones. Conversely, sintering proceeds through particle migration and coalescence in the absence of oxygen, leading to the aggregation of nanoparticles. The obtained Pt/CeO₂ catalysts exhibit enhanced catalytic performance after treatment with argon and stoichiometric reaction gases, contrasting with the deactivation observed under oxygen-rich conditions, which is attributed to varied Pt valence states. These findings provide insights into understanding the sintering mechanisms and inform the design of heterogeneous catalysts.