Polypyrrole-Modified-Carbon-Supported Ru-Pt Nanoparticles as Highly Methanol-Tolerant Electrocatalysts for the Oxygen-Reduction Reaction

The modification of mesoporous carbon black with polypyrrole (C-PP) facilitates the incorporation of homogeneously dispersed nanosized Ru-Pt particles (1-2nm) onto the support. Polypyrrole-modified carbon supports were prepared by the addition of different amounts of pyrrole, followed by insitu polymerization through oxidative treatments. The Ru-Pt/C-PP electrocatalysts were tested in the oxygen-reduction reaction in methanol-containing acidic electrolytes by using both conventional electrochemical techniques and in a direct methanol single cell. The performance of Ru-Pt/C-PP was far superior to that of Pt/C for the oxygen-reduction reaction in the direct methanol fuel cell. Under severe methanol-crossover conditions, the maximum power density that was delivered by Ru-Pt/C-PP after degradation tests was decreased by 20%, whereas that of Pt/C decreased by 75%. Thus, the presence of Ru oxides in the cathode led to more tolerant electrocatalysts towards the presence of methanol in the reaction medium during the oxygen-reduction reaction.