Investigation of ternary catalysts for methanol electrooxidation

The electrochemical oxidation of methanol was investigated on Pt-Ru-X terna ry metallic catalysts (with X=Au, Co, Cu, Fe, Mo, Ni, Sn or W). The catalys ts were prepared by electrochemical deposition and dispersed in a conductiv e three-dimensional matrix, an electronic conducting polymer, polyaniline ( PAni). A comparative study of the behaviour of several ternary catalysts to wards the electro-oxidation of methanol shows that PAni/Pt-Ru-Mo is the mos t efficient anode at potentials up to 500mV vs RHE. This latter ternary ele ctrocatalyst leads to current densities up to 10 times higher than those me asured with PAni/Pt-Ru in this potential range. Moreover, the catalyst appe ars to be stable for potentials lower than 550mV vs RHE. According to EDX a nalysis, the good behaviour of the Pt-Ru-Mo ternary catalyst seems to resul t from the presence of a small amount of the third metal, at an atomic rati o close to 5%. This set of encouraging results has also been confirmed by p reliminary measurements in a single cell direct methanol fuel cell (DMFC) c ontaining a home made PAni/Pt-Ru-Mo anode. The ternary catalyst leads to hi gher power densities than the PAni/Pt-Ru binary catalyst under the same exp erimental conditions.