【摘要】 在水/AOT/环己烷反胶束体系中,制备了Pt-Sn/C催化剂,研究了不同ω(反胶束溶液中水与表面活性剂的物质量之比)值对Pt-Sn粒径的影响.并采用TEM,XRD,XPS,循环伏安等技术对其进行表征.TEM结果表明合成的Pt-Sn纳米颗粒为球形,在碳载体表面均匀分布,粒径分布窄,平均粒径为2.7nm.Pt-Sn颗粒尺寸随着ω的增加而增大.XRD结果表明该催化剂中Pt具有面心立方结构且没有与Sn形成合金.XPS结果表明在该催化剂中,Pt主要以零价态存在.在甲醇溶液中的循环伏安扫描结果表明,甲醇氧化峰电位和峰电流随着ω的增加而减小,说明反胶束方法可以通过控制颗粒尺寸,从而影响催化剂的电氧化活性.相对于商用Pt-Ru/VulcanXC-72(20wt%,E-TEK公司),该催化剂具有较低的峰电势以及较高的If/Ib(循环伏安曲线中正向扫描峰电流与反向扫描峰电流的比值),这表明用此方法制备的Pt-Sn/C催化剂具有较好的抗中毒能力.更多还原

【Abstract】 Carbon supported catalyst Pt-Sn/C was synthesized in reverse micelle solution of water/AOT/ cyclohexane [AOT: bis-(2-ethylhexyl)sodium sulfosuccinate, (aerosol-OT)] and characterized by TEM, XRD, XPS and cyclic voltammetry (CV) techniques. TEM results showed that the Pt-Sn bimetallic particles were well dispersed on the carbon support with narrow size distribution and regular spherical shape. The av- erage size of the particles prepared is about 2.7 nm, and the particle size was increased with the increase of ω value (water-surfactant molar ratio). XRD results show that Pt has fcc crystalline structure and did not al- loyed with Sn. XPS results showed that the surface of the catalyst prepared was mainly covered by metallic platinum, Sn(II) and/or Sn(IV) species. CV results show that the methanol electrooxidation activity was de- creased with the increase of ω value, and the catalyst prepared has lower peak current potential and higher If/Ib [the ratio of the forward anodic peak current density (If) to the backward anodic peak current density (Ib) obtained from CV] than commercial catalyst of Pt-Ru/Vulcan XC-72 (20 wt% Pt-Ru, E-TEK company).更多还原