Tuning Single‐atom Pt₁−CeO₂ Catalyst for Efficient CO and C₃H₆ Oxidation: Size Effect of Ceria on Pt Structural Evolution

Abstract To reveal the effect of ceria particle size on dispersion and structure of supported Pt catalysts during preparation, activation, and reaction testing, a unique CeO₂/Al₂O₃ support (CA−c) with smaller CeO₂ particle size and more surface defects was prepared using a colloidal CeO₂ precursor, comparing with a conventional CeO₂/Al₂O₃ support (CA−n) using cerium nitrate as precursor. More atomically dispersed Pt and abundant Pt−O−Ce structures were observed in the Pt/CA−c catalyst than in the Pt/CA−n catalyst. Both parent catalysts received significant enhancement on their catalytic CO oxidation activities if activated by 10% hydrogen at 400 °C before reaction. Between the two representative catalysts, the extent of activity enhancement upon activation was more pronounced for Pt/CA−c. We found that smaller Pt clusters with more active ionic Pt sites were generated on the activated Pt/CA−c catalyst, while agglomerated larger Pt particles with more metallic sites were formed on the activated Pt/CA−n. The facile formation of Ce³⁺ was also indicative of more active metal‐support interfaces in the activated Pt/CA−c catalyst. These results highlight the importance of regulating ceria support particles to enable a controlled anchoring and subsequent activation of Pt single atoms for low‐temperature CO oxidation reaction.