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 evidences in recent reports suggest that Pt single atoms are exceptionally active catalytic sites. We demonstrate that infrared spectroscopy can be a fast and convenient characterization method to directly distinguish and quantify Pt single atoms from nanoparticles. In addition, we directly observe that only Pt nanoparticles show activity for CO oxidation and water-gas shift at low temperatures, while 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.

Published Online September 3 2015

Science DOI: 10.1126/science.aac6368

http://www.sciencemag.org/content/early/2015/09/02/science.aac6368.abstract