Performance of Pt-Ru/C Doped with Ho for Methanol Electro-Catalytic Oxidation

The Pt-Ru-Ho/C catalysts for methanol electro-oxidation have been prepared by pulse electro-deposition method. The activities of catalysts were characterized by cyclic voltammetry (CV) and electrochemical impedance spectrum (EIS). The microstructure and composition of the catalysts were characterized by XRD, EDS and XPS. The results show that Pt-based alloy nano-particles supported on carbon black consist of Pt, Ru, Ho elements, and the particle size and the specific surface of catalysts are about 3.5 nm and 73.3 m2·g−1, respectively. The electro-catalytic activity of Pt-Ru/C can markedly be improved by doping with Ho. The optimum mole fraction in Pt-Ru-Ho alloy nano-particle is nPt:nRu:nRu=1:1:0.2. Tafel constant a for Pt-Ru-Ho0.2/C is lower than that of Pt-Ru/C. The reaction order and the active energy of the methanol electro-oxidation are 0.17 and 28.4 kJ·mol−1, respectively.