Reaction-Driven Restructuring of Rh-Pd and Pt-Pd Core-Shell Nanoparticles
Feng Tao,1,2
Michael E. Grass,1,2
Yawen Zhang,1,2,5
Derek R. Butcher,1,2
James R. Renzas,1,2
Zhi Liu,1,3
Jen Y. Chung,3
Bongjin S. Mun,3
Miquel Salmeron,1,4*
Gabor A. Somorjai1,2*
Heterogeneous catalysts that contain bimetallic nanoparticles
may undergo segregation of the metals, driven by oxidizing and
reducing environments. The structure and composition of core-shell
Rh
0.5Pd
0.5 and Pt
0.5Pd
0.5 nanoparticle catalysts were studied
in situ, during oxidizing, reducing, and catalytic reactions
involving NO, O
2, CO, and H
2 by x-ray photoelectron spectroscopy
at near-ambient pressure. The Rh
0.5Pd
0.5 nanoparticles underwent
dramatic and reversible changes in composition and chemical
state in response to oxidizing or reducing conditions. In contrast,
no substantial segregation of Pd or Pt atoms was found in Pt
0.5Pd
0.5 nanoparticles. The different behaviors in restructuring and
chemical response of Rh
0.5Pd
0.5 and Pt
0.5Pd
0.5 nanoparticle
catalysts under the same reaction conditions illustrates the
flexibility and tunability of the structure of bimetallic nanoparticle
catalysts during catalytic reactions.
2 Department of Chemistry, University of California, Berkeley, CA 94720, USA.
3 Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
4 Department of Materials Science and Engineering, University of California, Berkeley, CA 94720, USA.
5 College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.
* To whom correspondence should be addressed. E-mail: somorjai{at}berkeley.edu (G.A.S.); mbsalmeron{at}lbl.gov (M.S.)
