Development of PtGe and PtIn anodic catalysts supported on carbonaceous materials for DMFC

Bimetallic PtGe and PtIn catalysts (Ge/Pt and In/Pt molar ratios = 0.33, 17 wt.% Pt loading) were prepared over carbonaceous supports (carbon Vulcan, carbon nanotubes and structured mesoporous carbon). The liquid phase deposition-reduction method by using 0.4 M sodium borohydride as a reducing agent was employed. The electrocatalytic activity for methanol oxidation was compared with a commercial Pt/CV E-TEK catalyst. The onset potential of the CO oxidation was shifted to less positive values for carbon Vulcan and carbon nanotubes supported catalysts and with a smaller effect in the case of mesoporous carbon supported ones. The best electrocatalytic performance was obtained by using carbon Vulcan as support of bimetallic catalysts, followed by carbon nanotubes. The performance of mesoporous carbon as a support was not adequate. PtGe/CV, PtGe/NT and PtIn/CV catalysts displayed the best performance in DMFC. The good performance of these catalysts could be due to the presence of small particle sizes with a narrow distribution, and to geometric effects (observed from different characterization techniques) related to a probable decoration of Ge or In around the small Pt particles.