The influence of acidic and alkaline precursors on Ptlyst performance for a direct methanol fuel cell

Abstract: This research aims to increase the activity of platinum–ruthenium alloy (Ptalysts for methanol electrooxidation. The direct methanol fuel cell (DMFC) anodic Ptlysts were prepared from acidic and alkaline Pt(NH3)2(NO2)2 solutions as Pt precursors, respectively, and with the same acidic Ru compound but without Cl− ion as the Ru precursor by thermal reduction. The phase structures, lattice parameters, particle sizes, alloy composition, distribution, and the morphology of reduced catalysts were determined by means of X-ray diffraction (XRD), energy-dispersive analysis of X-ray (EDAX), and high-resolution transmission electron microscopy (TEM). It was found that the XRD patterns of the two catalysts showed Pt reflections for a face centered cubic (fcc) crystalline alloy structure. The catalyst prepared from the acidic Pt(NH3)2(NO2)2 as a precursor has a more homogeneous distribution of Ptparticles on carbon. Its size is relatively small, about 3.7nm. Its chemical composition is quite similar to theoretical value of 1:1 (Pt:Ru). The catalyst prepared from the alkaline Pt(NH3)2(NO2)2 as a precursor has an uneven distribution of Ptles on carbon and its size is relatively large, and the chemical composition of Pt and Ru was 6:4. The performance was tested using a glassy carbon working electrode by cyclic voltammetry (CV) and chronoamperometric curves in a solution of 0.5molL−1 CH3OH and 0.5molL−1 H2SO4 at 25°C. The electrocatalytic activity of the Ptlyst prepared from the acidic Pt(NH3)2(NO2)2 as a precursor was the higher for methanol electrooxidation than that of catalyst from the alkaline source. The peak current density from the CV plot was 11.5mAcm−2. [Copyright &y& Elsevier]