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

1. Kunlun Ding1, 
2. Ahmet Gulec2, 
3. Alexis M. Johnson1, 
4. Neil M. Schweitzer3, 
5. Galen D. Stucky4, 
6. Laurence D. Marks2,
7. Peter C. Stair1,5,*

1. ¹Department of Chemistry, Northwestern University, Evanston, IL 60208, USA.
2. ²Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA.
3. ³Department of Chemical and Biological Engineering, Northwestern University, Evanston, IL 60208, USA.
4. ⁴Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA 93106, USA.
5. ⁵Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, IL 60439, USA.

1. ↵*Corresponding author. E-mail: pstair{at}northwestern.edu

Science 9 October 2015: 
Vol. 350 no. 6257 pp. 189-192 
DOI: 10.1126/science.aac6368

https://www.sciencemag.org/content/350/6257/189.short

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.