Nanoparticles of Pt hydrosol immobilised on Au support: an approach to thestudy of structural effects in electrocatalysis

The electrochemical properties of platinum hydrosol. obtained by the reduct ion of H2PtCl6 by sodium citrate (NaH(2)Cyt), were studied for the first ti me. Hydrosol particles of mean diameter d(c) approximate to 2.0 nm, as esti mated from UV-vis absorbance spectra. were immobilised on a Au support unde r anodic polarisation to form stable Pt-col/Au electrodes. High Pt coverage s were found from a combination of cyclic voltammetry and scanning tunnelli ng microscopy data. Immobilised Pt particles (most probably. small uniform aggregates) with tl, of about 4.5 nm and a spread of size distribution ca. 1.5 nm demonstrated pronounced adsorption of hydrogen and oxygen similar to pure Pt materials, high electrocatalytic activity with respect to formic a cid oxidation as well as a relatively high tolerance towards CO poisoning. (C) 2001 Elsevier Science Ltd. All rights reserved.