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Edited by Gabor A. Somorjai, University of California, Berkeley, CA, and approved May 9, 2013 (received for review March 20, 2013)
Abstract
The oxidation of bimetallic alloy nanoparticles comprising a noble and a nonnoble metal is expected to cause the formation of a single-component surface oxide of the nonnoble metal, surrounding a core enriched with the noble metal. Studying the room temperature oxidation of Au–In nanoparticles, we show that this simple picture does not apply to an important class of bimetallic alloys, in which the oxidation proceeds via predominant oxygen diffusion. Instead of a crystalline In2O3 shell, such oxidation leads to an amorphous shell of mixed Au–In oxide that remains stable to high temperatures and whose surface layer is enriched with Au. The Au-rich mixed oxide is capable of adsorbing both CO and O2 and converting them to CO2, which desorbs near room temperature. The oxidation of Au–In alloys to a mixed Au–In oxide shows significant promise as a viable approach toward Au-based oxidation catalysts, which do not require any complex synthesis processes and resist deactivation up to at least 300 °C.
Footnotes
- ↵1To whom correspondence should be addressed. E-mail: esutter{at}bnl.gov.
Author contributions: E.A.S. and P.W.S. designed research; E.A.S., X.T., K.J., and P.W.S. performed research; E.A.S. and P.W.S. analyzed data; and E.A.S. and P.W.S. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
Mixed Au–In oxides as stable Au nanocatalysts
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