铂铋金属间化合物催化剂的氧还原与抗甲醇氧化性能

采用氩弧熔炼后热处理方法制备了PtBi金属间化合物材料.采用循环伏安法和旋转圆盘电极进行电化学性能测试.通过在0.5 mol?L^－1 H₂SO₄＋0.25 mol?L^－1 CH₃OH溶液中对氧还原的起始电位和电流密度大小比较发现,与光滑铂电极相比,PtBi金属间化合物具有良好的氧还原催化性能和抗甲醇中毒性能.从结构方面分析了PtBi具有抗甲醇中毒性能的原因,认为是PtBi中Pt-Pt的间距大，不利于甲醇的吸附解离. X射线光电子能谱(XPS)结果表明,PtBi材料中Pt的d电子空穴增加,可能是导致PtBi电极表面氧还原电流增大的原因.

Intermetallic PtBi as Methanol-tolerant Catalysts for Oxygen Reduction

The electrochemical oxygen reduction at PtBi ordered intermetallic electrode surface has been investigated using cyclic voltammetry and rotating disk electrode. The results are compared to those at a polycrystalline platinum electrode surface. It was found that in methanol containing electrolyte solution the onset potential for oxygen reduction at PtBi is shifted to more positive potentials and the PtBi catalyst has about 4 times higher limiting current density for oxygen reduction than Pt. Thus the PtBi electrode exhibits superior properties in 0.5 mol?L^－1 H₂SO₄＋0.25 mol?L^－1 CH₃OH when compared to polycrystalline platinum in terms of oxygen reduction onset potential and current density. In ordered intermetallic PtBi, the Pt-Pt bond length is increased to 0.432 nm. This expansion makes it very difficult for methanol to adsorb on the PtBi surface, leading the PtBi to have the ability of resisting methanol. X-ray photoelectron spectroscopy analysis indicated an increased d-electron vacancy of the Pt in PtBi. Such an increase of 5d vacancies led to an increased 2π electron donation from O₂ to the Pt, resulting in an increased O₂ adsorption and a weakened O－O bond.