Tuning Single-atom Pt1-CeO2Catalyst for Efficient CO and C3H6Oxidation: Size Effect of Ceria on Pt Structural Evolution

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/Al(2)O(3)support (CA-c) with smaller CeO(2)particle size and more surface defects was prepared using a colloidal CeO(2)precursor, comparing with a conventional CeO2/Al(2)O(3)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 degrees 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 Ce(3+)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.