Tailoring the Local Environment of Platinum in Single-Atom Pt 1 /CeO 2 Catalysts for Robust Low-Temperature CO Oxidation.

A single-atom Pt ₁ /CeO ₂ catalyst formed by atom trapping (AT, 800 °C in air) shows excellent thermal stability but is inactive for CO oxidation at low temperatures owing to over-stabilization of Pt ²⁺ in a highly symmetric square-planar Pt ₁ O ₄ coordination environment. Reductive activation to form Pt nanoparticles (NPs) results in enhanced activity; however, the NPs are easily oxidized, leading to drastic activity loss. Herein we show that tailoring the local environment of isolated Pt ²⁺ by thermal-shock (TS) synthesis leads to a highly active and thermally stable Pt ₁ /CeO ₂ catalyst. Ultrafast shockwaves (>1200 °C) in an inert atmosphere induced surface reconstruction of CeO ₂ to generate Pt single atoms in an asymmetric Pt ₁ O ₄ configuration. Owing to this unique coordination, Pt ₁ ^δ+ in a partially reduced state dynamically evolves during CO oxidation, resulting in exceptional low-temperature performance. CO oxidation reactivity on the Pt ₁ /CeO ₂ _TS catalyst was retained under oxidizing conditions.
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