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Electrochemical Deposition of Platinum Nanoparticles on Carbon: A Study by Standard and Anomalous X‐ray Diffraction
Author(s) -
Adora Sébastien,
Simon Jean Paul,
SoldoOlivier Yvonne,
Faure René,
Chaînet Eric,
Durand Robert
Publication year - 2004
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.200301048
Subject(s) - platinum , platinum nanoparticles , nanoparticle , nucleation , electrochemistry , materials science , diffraction , electrode , carbon fibers , synchrotron , analytical chemistry (journal) , chemical engineering , nanotechnology , chemistry , catalysis , composite material , optics , organic chemistry , composite number , physics , engineering
Abstract This paper is devoted to an alternative method to characterize platinum nanoparticles: X‐ray powder diffraction with synchrotron radiation in classical and anomalous dispersion modes. We could straightforwardly determine the mean diameter and the surface concentration of carbon‐supported platinum nanoparticles, even down to diameters of 2–3 nm and catalyst amounts of 0.03 mg cm −2 . We could study early stages of the formation of electrochemically prepared platinum nanoparticles from [PtCl 4 ] 2− species preadsorbed on carbon inside a carbon–Nafion layer, to obtain a fuel‐cell electrode. Our X‐ray diffraction (XRD) results demonstrate that, provided the superficial concentration is not too high, new and smaller particles appear for each current pulse, since there is not any strong nucleation limitation for the high overvoltages obtained. Hydrogen evolution becomes the main electrochemical phenomenon on particles of sufficient size and it explains the noteworthy size limitation. Better yields of Pt metal are obtained for smaller current densities and longer times: the rate‐determining step is then not electrochemical, but chemical or related to superficial diffusion.