石墨烯负载PtPd纳米催化剂的合成及其电催化氧化甲醇性能

采用改进的Hummers法制备氧化石墨烯,然后以其为载体前驱体,以三嵌段共聚物P123为还原剂、保护剂和形貌控制剂,分别采用液相共还原法和连续还原法,制备了三种石墨烯负载PtPd(PtPd/G)纳米催化剂;氧化石墨烯与金属前驱体同步还原,从而达到原位负载的效果。采用X射线衍射(XRD)、透射电镜(TEM)、X射线光电子能谱(XPS)等表征方法分析了PtPd/G纳米催化剂的形貌、结构和组成,结果表明:采用共还原法得到的两种催化剂均为纳米枝结构;采用连续还原法得到了空心纳米结构。电化学循环伏安法和计时电流法研究表明:空心结构PtPd/G纳米催化剂抗CO中毒能力最强,100°C下共还原合成的PtPd/G纳米枝催化剂具有最佳的电催化氧化甲醇性能,约是商业化Pt/C催化剂的1.5倍。

Synthesis and Electrocatalytic Properties of PtPd Nanocatalysts Supported on Graphene for Methanol Oxidation

This work describes the preparation of three kinds of PtPd/graphene (PtPd/G) nanocatalysts. Graphene oxide was first prepared as the carrier precursor by the Hummers method, and subsequently, the simultaneous reduction of graphene oxide and the metal precursor led to the in situ loading of PtPd on graphene. The fabrication procedure involving liquid phase co-reduction and successive reduction methods utilized the block copolymer P123 as a reducing agent, stabilizer, and morphology control agent. The morphology, structure, and composition of the obtained catalysts were studied by X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). It was found that the catalysts synthesized by the co-reduction method possess a nanodendritic structure, while those prepared by successive reduction exhibit a hollow structure. Cyclic voltammetry and chronoamperometry investigations revealed that the PtPd/G catalyst with a hollow structure displayed the best anti-CO poisoning properties. In contrast, the catalyst with a dendritic structure that had been prepared at 100℃ showed the highest electrocatalytic performance towards methanol oxidation, which was 1.5 times that of the commercial Pt/C electrocatalyst.