Pt and Pt-Ru nanoparticles decorated polypyrrole/multiwalled carbon nanotubes and their catalytic activity towards methanol oxidation

Conducting polymer composite films comprised of polypyrrole (PPy) and multiwalled carbon nanotubes (MWCNTs) [PPy-CNT] were synthesized by in situ polymerization of pyrrole on carbon nanotubes in 0. 1 M HCl containing (NH4)S2O8 as oxidizing agent over a temperature range of 0-5 degrees C. Pt nanoparticles are deposited on PPy-CNT composite films by chemical reduction of H2PtCl6 using HCHO as reducing agent at pH = 11 [Pt/PPy-CNT]. The presence of MWCNTs leads to higher activity, which might be due to the increase of electrochemically accessible surface areas, electronic conductivity and easier charge-transfer at polymer/electrolyte interfaces allowing higher dispersion and utilization of the deposited Pt nanoparticles. A comparative investigation was carried out using Pt-Ru nanoparticles decorated PPy-CNT composites. Cyclic voltammetry demonstrated that the synthesized Pt-Ru/PPy-CNT catalysts exhibited higher catalytic activity for methanol oxidation than Pt/PPy-CNT catalyst. Such kinds of Pt and Pt-Ru particles deposited on PPyCNT composite polymer films exhibit excellent catalytic activity and stability towards methanol oxidation, which indicates that the composite films is more promising support material for fuel cell applications. (c) 2007 Elsevier B.V. All rights reserved.