Identification of active sites in CO oxidation and water-gas shift over supported Pt catalysts

TLDR

Identifying and characterizing catalytic active sites is essential for atomic‑level understanding of mechanisms and rational design of high‑performance heterogeneous catalysts, and recent indirect evidence indicates that platinum single atoms are exceptionally active sites. The study aims to demonstrate that infrared spectroscopy can rapidly and conveniently distinguish and quantify Pt single atoms from nanoparticles. Infrared spectroscopy was employed to directly distinguish and quantify Pt single atoms versus nanoparticles. Only Pt nanoparticles are active for CO oxidation and water‑gas shift at low temperatures, while Pt single atoms act as spectators, likely because of strong CO binding.

Abstract

Identification and characterization of catalytic active sites are the prerequisites for an atomic-level understanding of the catalytic mechanism and rational design of high-performance heterogeneous catalysts. Indirect evidence in recent reports suggests that platinum (Pt) single atoms are exceptionally active catalytic sites. We demonstrate that infrared spectroscopy can be a fast and convenient characterization method with which to directly distinguish and quantify Pt single atoms from nanoparticles. In addition, we directly observe that only Pt nanoparticles show activity for carbon monoxide (CO) oxidation and water-gas shift at low temperatures, whereas Pt single atoms behave as spectators. The lack of catalytic activity of Pt single atoms can be partly attributed to the strong binding of CO molecules.