文摘
Pt3Sn/C catalyst was prepared by a modified polyol process and treated in air, H2/Ar, and Aratmosphere, respectively. XRD analyses indicate that all of these catalysts have face-centeredcubic (fcc) crystal structure. Temperature-programmed reduction (TPR) experiments show thatmore Sn exists in zero-valence in the Ar-treated PtSn catalyst than in the others. Cyclicvoltammetry (CV), chronoamperometry (CA) experiments, and the performance tests of directethanol fuel cell (DEFC) indicate that the catalytic activity of PtSn/C for ethanol oxidation wasaffected significantly by the chemical state of Sn in catalyst particles. The as-prepared PtSn/Cgives the higher power density, while Ar-treated PtSn/C shows the lower cell performance. Itseems that the multivalence Sn rather than the zero-valence Sn in the PtSn catalyst is thefavorable form for ethanol oxidation. Energy dispersion X-ray analysis (EDX) of the PtSn/C-asprepared and PtSn/C (after stability test) shows the active species (platinum, tin, and oxygen)composition changed to a different extent. Further attempt to improve the catalyst stability isneeded.