Stable Pt-Ru/C catalysts prepared from new precursors by thermal reduction for direct methanol fuel cell

This research is aimed at improving the activity of Pt-Ru alloy catalysts, thus to lower the catalyst loading in anodes for methanol electro-oxidation. The direct methanol fuel cell's (DMFC's) anodic catalysts as Pt-Ru/C were prepared from Pt(NH₃)₂(NO₂)₂ and self-prepared Ru compound as precursors at different temperatures and times of duration during their reduction. Their performances were examined by cyclic vóltammetry and chronoamperometry with a glassy carbon working electrode made from them. The particle size and its distribution of the catalysts were determined by means of transmission electron microscopy and X-ray diffraction. The activity and stability of Pt-Ru/C catalysts prepared from Pt(NH ₃)₂(NO₂)₂ and self-prepared Ru compound as precursors is higher than those from H₂PtCl₆ and RuCl₃ by chemical or thermal reduction. The times and temperatures of thermal reduction affect the performance of Pt-Ru/C catalysts. The particle size of Pt-Ru/C catalysts increases with increasing temperature. The catalytic activity of Pt-Ru/C catalysts prepared at 360°C is higher than that of those prepared at 320 and 400°C, The particle size of Pt-Ru/C catalysts increases with the duration of reduction time. After 2 h at 360°C of reduction it is small, about 3.7 nm, and the catalytic activity is higher than those after 1 and 3 h of reduction.