中文摘要：

在超临界二氧化碳的辅助下,使用乙酰丙酮铂和乙酰丙酮钌作为前驱体,甲醇作为共溶剂,H2作为还原剂,在200℃将PtRu纳米颗粒还原负载在石墨烯（EG）上.制备产物的形貌和微结构用X射线衍射（XRD）、X射线光电子能谱（XPS）和透射电子显微镜（TEM）进行了分析.同时,用相同的方法制备了PtRu/C（炭黑Vulcan XC-72）复合材料,将其与PtRu/EG对于甲醇氧化的电催化活性和稳定性也通过循环伏安和计时电流法进行了比较.研究证实,用超临界流体方法沉积在石墨烯上的PtRu纳米颗粒具有较小的平均粒径和尺寸分布.与PtRu/C相比,PtRu/EG复合材料对于甲醇电氧化展示出更高的电催化活性和稳定性.

英文摘要：

We present a simple and effective supercritical fluid route to uniformly load ultrafine metal nanoparticles on the hydrophobic surfaces of graphene sheets.In the presence of supercritical carbon dioxide,PtRu alloy nanoparticles are decorated evenly on expansion graphene （EG） upon the reduction of organic platinum and ruthenium precursors,and its application as an electrocatalyst for methanol oxidation is studied.Transmission electron microscopy,X-ray diffraction and X-ray photoelectron spectroscopy analysis were used to study the resulted composites.Compared with the widely used Vulcan XC-72 carbon black,the PtRu/EG composites exhibit superior catalytic activity and stability for methanol oxidation.The huge surface area of graphene and uniform distribution of nanosized metal particles are two critical factors for the significantly enhanced electrocatalytic efficiency.The findings suggest that the supercritical fluid method is highly efficient in preparing graphene-supported metallic catalysts,and EG serve as a favorable electrocatalytic carrier for direct methanol fuel cells.