Investigations of compositions and performance of PtRuMo/C ternary catalysts for methanol electrooxidation

PtRuMo/C catalyst was prepared by impregnation reduction method and characterised. Comparison is made between a home-made PtRu/C prepared by similar method and Pt/C (E-Tek Co., Pt/C-ET) catalysts. One glassy carbon disc electrode for ternary alloy catalyst was used to evaluate the catalytic performances by cyclic voltammetric, chronoamperometric, amperometric i-t curves, and electrochemical impedance spectra (EIS). The electrochemical measurement results indicated that the performance of PtRuMo/C with a molar ratio of 6:3:1 was the highest among 15 PtxRuyMo10-x-y/C catalysts with different molar ratios. The composition, particle size, lattice parameter and morphology of the PtRuMo(6:3:1)/C catalyst were determined by means of X-ray energy dispersive analysis, X-ray diffraction (XRD) and transmission electron micrographs (TEM). The result of XRD analysis exhibits that PtRuMo(6:3:1)/C has the fcc structure with the smaller lattice parameter than the home-made PtRu/C and Pt/C-ET. Its typical particle sizes is only about 5 nm. With respect to the catalytic activity and stability, the PtRuMo(6:3:1)/C catalys is superior to PtRu/C despite their comparable active areas. Though the electrochemically active surface area of Pt/C-ET is the biggest, its performance is the lowest. EIS results also indicate that the reaction resistances for methanol electrooxidation on the PtRuMo(6:3:1)/C catalyst are smaller than those of PtRu/C at different polarisation potentials.