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Influence of Particle Agglomeration on the Catalytic Activity of Carbon-Supported Pt Nanoparticles in CO Monolayer Oxidation Full article

Общее Language: Английский, Genre: Full article,
Status: Published, Source type: Original
Journal PCCP: Physical Chemistry Chemical Physics
ISSN: 1463-9076 , E-ISSN: 1463-9084
Output data Year: 2005, Volume: 7, Number: 2, Pages: 385-393 Pages count : 9 DOI: 10.1039/b411377b
Authors Maillard F. 1 , Schreier S. 1 , Hanzlik M. 1 , Savinova E.R. 1,3 , Weinkauf S. 2 , Stimming U. 1
Affiliations
1 Technical University of Munich
2 Technical University of Munich
3 Boreskov Institute of Catalysis SB RAS

Funding (2)

1 German Research Foundation Sti74/8-4
2 Federal Ministry of Education and Research 01SF 0201

Abstract: Fuel cell electrocatalysts usually feature high noble metal contents, and these favour particle agglomeration. In this paper a variety of synthetic approaches (wet chemical deposition, electrodeposition and electrodeposition on chemically preformed Pt nuclei) is employed to shed light on the influence of nanoparticle agglomeration on their electrocatalytic properties. Pt loading on model glassy carbon (GC) support is increased systematically from 1.8 to 10.6 μg Pt cm−2 and changes in the catalyst structure are followed by transmission electron microscopy. At low metal loadings (≤5.4 μg Pt cm−2) isolated single crystalline Pt nanoparticles are formed on the support surface by wet chemical deposition from H2PtCl4 precursor. An increase in the metal loading results, first, in a systematic increase of the average diameter of isolated Pt nanoparticles and, second, in coalescence of nanoparticles and formation of particle agglomerates. This behaviour is in line with the previous observations on carbon-supported noble metal fuel cell electrocatalysts. The catalytic activity of Pt/GC electrodes is tested in CO monolayer oxidation. In agreement with the previous studies (F. Maillard, M. Eikerling, O. V. Cherstiouk, S. Schreier, E. Savinova and U. Stimming, Faraday Discuss., 2004, 125, 357), we find that the reaction is strongly size sensitive, exhibiting an increase of the reaction overpotential as the particle size decreases below ca. 3 nm. At larger particle sizes the dependence levels off, the catalytic activity of particles with diameters above 3 nm approaching that of polycrystalline Pt. Meanwhile, Pt agglomerates show remarkably enhanced catalytic activity in comparison to either isolated Pt nanopraticles or polycrystalline Pt foil, catalysing CO monolayer oxidation at ca. 90 mV lower overpotential. Enhanced catalytic activity of Pt agglomerates is ascribed to high concentration of surface defects. CO stripping voltammograms from Pt/GC electrodes, comprising Pt agglomerates along with isolated single crystalline Pt nanoparticles from 2 to 6 nm size, feature double voltammetric peaks, the more negative corresponding to CO oxidation on Pt agglomerates, while the more positive to CO oxidation on isolated Pt nanoparticles. It is shown that CO stripping voltammetry provides a fingerprint of the particle size distribution and the extent of particle agglomeration in carbon-supported Pt catalysts.
Cite: Maillard F. , Schreier S. , Hanzlik M. , Savinova E.R. , Weinkauf S. , Stimming U.
Influence of Particle Agglomeration on the Catalytic Activity of Carbon-Supported Pt Nanoparticles in CO Monolayer Oxidation
PCCP: Physical Chemistry Chemical Physics. 2005. V.7. N2. P.385-393. DOI: 10.1039/b411377b publication_identifier_short.wos_identifier_type publication_identifier_short.scopus_identifier_type publication_identifier_short.rinz_identifier_type
Dates:
Submitted: Jul 26, 2004
Accepted: Nov 2, 2004
Published online: Nov 19, 2004
Identifiers:
publication_identifier.wos_identifier_type WOS:000225888400021
publication_identifier.scopus_identifier_type 2-s2.0-12744280748
publication_identifier.rinz_identifier_type 43194526
publication_identifier.accession_number_identifier_type 2004:1131287
publication_identifier.chemical_accession_number_identifier_type 142:243537
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