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

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Science  09 Oct 2015:
Vol. 350, Issue 6257, pp. 189-192
DOI: 10.1126/science.aac6368

Comparing active site reactivity

Noble metal nanoparticles often exhibit behaviors distinct from atomic and bulk versions of the same material. Gold and platinum dispersed on metal oxide supports, for example, show remarkable low-temperature reactivity for carbon monoxide (CO) oxidation by oxygen or water. Ding et al. used infrared spectroscopy to identify CO adsorbed on isolated platinum atoms or nanoparticles dispersed on zeolite and oxide supports. Temperature-programmed desorption studies showed that CO reacted at much lower temperatures when adsorbed on nanoparticles versus on isolated metal atoms.

Science, this issue p. 189


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.

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