用于燃料电池Co@Pt/C核壳结构催化剂的制备及表征

采用两步化学还原法制备了Co@Pt/C电催化剂, 并在还原气氛下对催化剂进行热处理. 通过高分辨透射电镜(HR-TEM)和X射线光电子能谱(XPS)等技术对催化剂的微观结构和形貌进行表征. 结果表明: 形成的Co@Pt/C催化剂具有核壳结构, 金属纳米颗粒均匀负载于碳上, 其粒径分布范围较窄; 热处理对催化剂的结构和形貌有较大影响. 利用循环伏安(CV)法和线性伏安扫描(LSV)法表征催化剂的电化学活性、氧还原反应(ORR)动力学特性及耐久性. 制备的Co@Pt/C催化剂在电解质溶液中表现出良好的电化学性能, 核壳结构的形成有助于提高Pt 的利用率. 动力学性能测试表明催化剂的ORR反应以四电子路线进行. 相比于合金催化剂,核壳结构催化剂的耐久性和稳定性有很大程度的改善.

Preparation and Characterization of Core-Shell Co@Pt/C Catalysts for Fuel Cell

Co@Pt/C core-shell catalysts have been synthesized by a two-step chemical reduction method, followed by heat treatment in a H₂ and N₂ mixture. High resolution transmission electron microscopy (HR-TEM) and X-ray photoelectron spectroscopy (XPS) techniques were used to characterize the catalyst microstructure and morphology. The results indicate that the core-shell structure of Co rich in core and Pt rich in shell is formed and the nano-particles are highly dispersed on the surface of the carbon support. Heat treatment affects the structure and morphology of the catalysts. The electrocatalytic performance, kinetic characteristics of O₂ reduction reaction (ORR), and durability of the catalysts were measured by cyclic voltammetry (CV) and linear sweep voltammetry (LSV) techniques. It was found that the formation of the core-shell structure is favorable for improving the performance and utilization of Pt. The Co@Pt/C catalyst mechanism proceeds by an approximately four-electron pathway in acid solution, through which molecular oxygen is directly reduced to water. Compared with alloy catalysts, the formation of the core-shell structure obviously improves the catalyst durability.