Oxide supported Pt-based heterogeneous catalysts accelerate many critical reactions for chemical conversion. Utilizing all individual Pt atoms as a reaction site is a promising route for sustainable use of earth unabundant and expansive Pt. However, thermodynamic vulnerability of Pt single-atoms (SAs) under the reaction conditions questions the practical value of Pt-SAs. Moreover, whether the inherent catalytic nature of Pt-SAs is superior to that of the larger Pt clusters of nanoparticles is under debate. In this study, we address above critical controversies by comparatively studying the catalytic activity and stability of Pt-SAs supported on a conventional TiO₂ or a precisely designed CeO_x/TiO₂ hybrid-oxide support toward environmentally relevant CO oxidation reaction. By utilizing the heterogeneous interface formed between TiO₂ supporting particles and CeO_x clusters formed on the surface of TiO₂, we preferentially synthesized Pt-SAs pinned at the CeO_x-TiO₂ interfaces on CeO_x-TiO₂ hybrid-oxide supports. The strong electronic coupling between the Pt-SAs and the Ce ions at the CeO_x-TiO₂ interfaces promoted the catalytic activity toward CO oxidation of Pt-SAs and improved the long-term stability under the CO oxidation conditions. The CO oxidation activity of Pt-SAs stabilized at the CeO_x-TiO₂ was improved by 13.5 times at 200 °C compared with the Pt-SAs on TiO₂. The results present how to easily improve the activity and stability of Pt-SAs using simple interface control method. Our study delivers comprehensive understating about the catalytic nature as well as a novel strategy toward applications of Pt-SAs, enabling sustainable use of Pt in heterogeneous catalysts.

David Shapiro

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