States of Pt/CeO2 catalysts for CO oxidation below room temperature

[Display omitted] •Oxidation states and CO oxidation activity of Pt/CeO2 catalysts are affected by pretreatments, Pt loading, and exposure to reaction conditions.•Atomically dispersed Pt2+ species are reduced to Ptn clusters under reductive pretreatments, and Ptn clusters are oxidized to stable PtOx...

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Published in:Journal of catalysis 2023-05, Vol.421, p.285-299
Main Authors: Slavinskaya, Elena M., Stadnichenko, Andrey I., Quinlivan Domínguez, Jon E., Stonkus, Olga A., Vorokhta, Mykhailo, Šmíd, Břetislav, Castro-Latorre, Pablo, Bruix, Albert, Neyman, Konstantin M., Boronin, Andrei I.
Format: Article
Language:English
Subjects:
low-temperature CO oxidation
Pt/CeO2
PtOx clusters
Single atom
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Summary:[Display omitted] •Oxidation states and CO oxidation activity of Pt/CeO2 catalysts are affected by pretreatments, Pt loading, and exposure to reaction conditions.•Atomically dispersed Pt2+ species are reduced to Ptn clusters under reductive pretreatments, and Ptn clusters are oxidized to stable PtOx clusters during CO oxidation reaction.•PtOx particles are more active than Pt particles at sub-ambient temperatures, and Pt particles are more active than atomically dispersed Pt2+ species.•PtOx particles are more stable than Pt particles, and as stable as atomically dispersed Pt2+ species. CO molecules can be efficiently oxidized over Pt/CeO2 catalysts, but the stability and reactivity of different states of Pt in the catalysts are still unclear. Here we combine experimental and computational methods to characterize Pt/CeO2 catalysts subjected to reductive and oxidative pre-treatments and exposed to CO oxidation reaction conditions. Particles of metallic Pt, known to be catalytically active at elevated temperature, are shown to be precursors for the formation, under operando conditions, of more stable PtOx particles that enable CO oxidation below room temperature. These PtOx particles are similarly stable to – but more active than – atomically dispersed Pt2+ species. The results and approaches presented in this study illustrate the complex response of catalytic materials to reaction conditions and pave the way for future efforts to improve Pt/CeO2 and similar catalysts using dedicated pre-treatment strategies.
ISSN:0021-9517
1090-2694
DOI:10.1016/j.jcat.2023.03.004