(261e) An Atomic-Scale View of Single-Site Pt Catalysis for Low-Temperature CO Oxidation

Single-atom catalysts have attracted great attention in recent years due to their high efficiencies and cost savings. However, there is debate concerning the nature of the active site, interaction with the support, and mechanism by which single-atom catalysts operate. Here, using a combined surface science and theory approach, we designed a model system in which we unambiguously show that individual Pt atoms on a well-defined Cu₂O film are able to perform CO oxidation at low temperatures (Figure 1). Isotopic labelling studies reveal that oxygen is supplied by the support. Density functional theory rationalizes the reaction mechanism and confirms X-ray photoelectron spectroscopy measurements of the neutral charge state of Pt. Scanning tunneling microscopy enables visualization of the active site as the reaction progresses, and infrared measurements of the CO stretch frequency are consistent with atomically dispersed Pt atoms. These results serve as a benchmark for characterizing, understanding and designing other single-atom catalysts.

Figure 1. 3D-rendered 5 Kelvin STM image of single Pt atoms on a Cu₂O thin film. Schematic shows CO oxidation via a Mars van Krevelen mechanism in which an oxygen atom from the Pt/Cu₂O interface oxidizes the CO molecule bound to the Pt atom.