Single atom catalysts (SACs) have attracted attention because of improved atom efficiency, higher reactivity, and better selectivity. A major challenge is to achieve high surface concentrations while preventing these atoms from agglomeration at elevated temperatures. Techniques such as XPS, LEIS, XAS, TEM and DFT, demonstrate that ceria can support Pt single atoms at high metal loading (3wt%Pt), without forming any clusters when heated in air at 800°C. The mechanism of trapping involves a reaction of the mobile PtO2 with under-coordinated cerium cations present at CeO2(111) step edges. Moreover, using a synthesis temperature of 800°C (atom trapping–AT) has benefits compared to conventional synthesis methods that use lower synthesis temperature (strong electrostatic adsorption–SEA). AT and SEA catalysts are SACs in the as-synthesized state and are inactive for low temperature (&lt;150°C) CO oxidation. After activation, both catalysts show enhanced reactivity but the AT shows the best results. NAP-XPS and CO-TPR show that the high reactivity at low temperature can be related to the improved reducibility of lattice oxygen on CeO2.

Synthesis of high metal loading thermally stable Pt/CeO2 single-atom catalysts and activation of O2 on CeO2 for low temperature CO oxidation

2019 Fall National Meeting

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