Investigation of Ternary Catalysts for Methanol Electrooxidation

The electrochemical oxidation of methanol was investigated on Pt–Ru–X ternary metallic catalysts (with X=Au, Co, Cu, Fe, Mo, Ni, Sn or W). The catalysts were prepared by electrochemical deposition and dispersed in a conductive three-dimensional matrix, an electronic conducting polymer, polyaniline (PAni). A comparative study of the behaviour of several ternary catalysts towards the electro-oxidation of methanol shows that PAni/Pt–Ru–Mo is the most efficient anode at potentials up to 500mV vs RHE. This latter ternary electrocatalyst leads to current densities up to 10 times higher than those measured with PAni/Pt–Ru in this potential range. Moreover, the catalyst appears to be stable for potentials lower than 550mV vs RHE. According to EDX analysis, the good behaviour of the Pt–Ru–Mo ternary catalyst seems to result from the presence of a small amount of the third metal, at an atomic ratio close to 5%. This set of encouraging results has also been confirmed by preliminary measurements in a single cell direct methanol fuel cell (DMFC) containing a home made PAni/Pt–Ru–Mo anode. The ternary catalyst leads to higher power densities than the PAni/Pt–Ru binary catalyst under the same experimental conditions.

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