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

Abstract

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.