Facile synthesis of hollow spherical sandwich PtPd/C catalyst by electrostatic self-assembly in polyol solution for methanol electrooxidation

摘要

A novel PtPd/C catalyst with hollow spherical structure has been successfully prepared by electrostatic self-assembly one-step reductive route using sodium dodecyl sulfate as a capping and structure-directing agent in ethylene glycol solution by microwave-assisted process. The structure, composition, and morphology of as-prepared catalyst are characterized by X-ray diffraction, energy dispersive analysis of X-ray, scanning electron microscope, and transmission electron micrograph, respectively. The as-prepared PtPd/C catalyst has a novel hollow spherical sandwich structure with open porosity and integrity, which can prevent Pd metal from oxidation and dissolution, and enhance electrocatalytic activity and stability toward methanol electrooxidation in comparison with the solid solution PtPd/C alloy and Pt/C catalysts. The results of electrochemical measurement demonstrate the enhancement of the CO-tolerant ability of hollow spherical PtPd/C catalyst by the new insight into the mechanism that Pd can efficiently directly oxidize the poisoning intermediates from methanol electrooxidation, such as HCOOH, to CO_2, which promotes its catalytic efficiency and results in much higher electrocatalytic activity than Pt/C on a mass basis. Therefore, the effective and facile method to prepare PtPd/C catalyst with hollow spherical sandwich and porous structure and better catalytic performance is very important and desirable in direct methanol fuel cell applications.