Atomic-scale identification of Pd leaching in nanoparticle catalyzed C-C coupling: effects of particle surface disorder.

Autor:	Briggs BD; Department of Chemistry , University of Miami , 1301 Memorial Drive , Coral Gables , Florida 33146 , USA . Email: knecht@miami.edu., Bedford NM; Materials and Manufacturing Directorate , Air Force Research Laboratory , Wright-Patterson Air Force Base , Ohio 45433 , USA.; Department of Chemistry , University of Miami , 1301 Memorial Drive , Coral Gables , Florida 33146 , USA . Email: knecht@miami.edu.; Applied Chemicals and Materials Division , National Institute of Standards and Technology , 325 Broadway , Boulder , Colorado 80305 , USA., Seifert S; X-Ray Science Division , Argonne National Laboratory , 9700 S. Cass Ave , Argonne , Illinois 60439 , USA., Koerner H; Materials and Manufacturing Directorate , Air Force Research Laboratory , Wright-Patterson Air Force Base , Ohio 45433 , USA., Ramezani-Dakhel H; Department of Polymer Engineering , University of Akron , Akron , Ohio 44325 , USA., Heinz H; Department of Polymer Engineering , University of Akron , Akron , Ohio 44325 , USA., Naik RR; Materials and Manufacturing Directorate , Air Force Research Laboratory , Wright-Patterson Air Force Base , Ohio 45433 , USA., Frenkel AI; Department of Physics , Yeshiva University , 245 Lexington Ave , New York , New York 10016 , USA., Knecht MR; Department of Chemistry , University of Miami , 1301 Memorial Drive , Coral Gables , Florida 33146 , USA . Email: knecht@miami.edu.
Jazyk:	angličtina
Zdroj:	Chemical science [Chem Sci] 2015 Nov 01; Vol. 6 (11), pp. 6413-6419. Date of Electronic Publication: 2015 Jul 23.
DOI:	10.1039/c5sc01424g
Abstrakt:	C-C coupling reactions are of great importance in the synthesis of numerous organic compounds, where Pd nanoparticle catalyzed systems represent new materials to efficiently drive these reactions. Despite their pervasive utility, the catalytic mechanism of these particle-based reactions remains highly contested. Herein we present evidence of an atom leaching mechanism for Stille coupling under aqueous conditions using peptide-capped Pd nanoparticles. EXAFS analysis revealed Pd coordination changes in the nanoparticle consistent with Pd atom abstraction, where sizing analysis by SAXS confirmed particle size changes associated with a leaching process. It is likely that recently discovered highly disordered surface Pd atoms are the favored catalytic active sites and are leached during oxidative addition, resulting in smaller particles. Probing the mechanism of nanoparticle-driven C-C coupling reactions through structural analyses provides fundamental information concerning these active sites and their reactivity at the atomic-scale, which can be used to improve catalytic performance to meet important sustainability goals.
Databáze:	MEDLINE
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