Pt1–O4 as active sites boosting CO oxidation via a non-classical Mars–van Krevelen mechanism

Abstract

Single-atom catalysts (SACs) exhibit excellent performance for various catalytic reactions but it is still challenging to have adequate total activity for practical applications. Here we report the high-valence, square planar Pt₁–O₄ as an active site that enables significantly to increase the total activity of the Pt₁/Fe₂O₃ SAC with a Pt loading of only ∼30 ppm, which is similar to that of a 1.0 wt% nano-Pt/Fe₂O₃, for CO oxidation at 350 °C. Density functional theory calculations reveal that Pt₁–O₄ catalyzes CO oxidation through a non-classical Mars–van Krevelen mechanism. The adsorbed O₂ on Pt₁ atoms activates the coordination oxygen in the Pt₁–O₄ configuration, and then a barrierless O₂ dissociation occurs on the Pt₁–Fe₂ triangle to replenish the consumed coordination oxygen by the cooperative action of Pt 5d and Fe 3d electrons. This work provides a new fundamental understanding of oxidation catalysis on stable and active SACs, providing guidance for rationally designing future heterogeneous catalysts.