Fabrication of Pt nanoparticles decorated PPy–MWNTs composites and their electrocatalytic activity for methanol oxidation

Here we report the synthesis and characterization of a catalyst material constituted of Pt, polypyrrole (PPy) and multi-walled carbon nanotubes (MWNTs). The catalyst supports (PPy–MWNTs nanocomposites) were synthesized via in situ chemical polymerization in advance, in which MWNTs were regarded as the matrix material. The supports were characterized by SEM & TEM, elemental analysis, XRD, FTIR and conductivity measurements. Then the catalysts were synthesized by a chemical reduction using sodium borohydride (NaBH₄) as reducing agent and acetic acid buffer (pH = 4) containing trace K₂C₂O₄ as reaction media. FTIR spectra showed that there existed relations between PPy and MWNTs during in situ polymerization. SEM and TEM micrographs of the catalyst samples exhibited that the existence of PPy layer which was evenly wrapped on the surface of MWNTs resulted in significant improvement in helping Pt particles well dispersed. XRD results showed that higher Pt(1 1 1) content in the catalyst deposited on PPy–MWNTs supports than that on MWNTs. The cyclic voltammetry (CV) tests of methanol electrocatalytic oxidation demonstrated that the electrode modified by Pt/PPy–MWNTs ternary composite catalyst showed higher catalytic stability than Pt/MWNTs binary catalyst, due to the synergic interaction between Pt and the carrier.