Co-catalytic effect of Ni in the methanol electro-oxidation on Pt–Ru/C catalyst for direct methanol fuel cell

Abstract

This research is aimed to improve the utilization and activity of anodic catalysts, thus to lower the contents of noble metals loading in anodes for methanol electro-oxidation. The direct methanol fuel cell anodic catalysts, Pt–Ru–Ni/C and Pt–Ru/C, were prepared by chemical reduction method. Their performances were tested by using a glassy carbon working electrode through cyclic voltammetric curves, chronoamperometric curves and half-cell measurement in a solution of 0.5 mol/L CH₃OH and 0.5 mol/L H₂SO₄. The composition of the Pt–Ru–Ni and Pt–Ru surface particles were determined by EDAX analysis. The particle size and lattice parameter of the catalysts were determined by means of X-ray diffraction (XRD). XRD analysis showed that both of the catalysts exhibited face-centered cubic structures and had smaller lattice parameters than Pt-alone catalyst. Their sizes are small, about 4.5 nm. No significant differences in the methanol electro-oxidation on both electrodes were found by using cyclic voltammetry, especially regarding the onset potential for methanol electro-oxidation. The electrochemically active-specific areas of the Pt–Ru–Ni/C and Pt–Ru/C catalysts are almost the same. But, the catalytic activity of the Pt–Ru–Ni/C catalyst is higher for methanol electro-oxidation than that of the Pt–Ru/C catalyst. Its tolerance performance to CO formed as one of the intermediates of methanol electro-oxidation is better than that of the Pt–Ru/C catalyst.