Preparation, Characterization And Property Of Electrocatalysts Graphene Supported On For Fuel Cell

Proton exchange membrane fuel cell (PEMFC) is a kind of environment protected power generating mode with high energy density. At present, the main electrocatalysts of PEMFCs are metallic platinum materials. The insufficient activity and high cost of Pt, however, are the major obstacles for the commercialization of fuel cells. In this dissertation, electrocatalytic activity of the electrocatalysts for PEMFC was improved by preparing new structure, changing to new supports and applying assistant catalysts. The morphologies, structures, phases and electrochemical properties of the catalysts have been investigated with scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), X-ray diffraction (XRD) and cyclic voltammetry (CV). The main points in this dissertation are summarized as follows:(1) Graphene oxide (GO) was synthesized from natural graphite by a modified Hummer's method. Ag/Graphene catalysts were prepared via different routes. The electrocatalytic activity of the catalysts for the oxidation of hydrazine (N2H4) and formaldehyde (HCHO) were investigated. The results indicated that Ag/Graphene catalysis showed excellent electrocatalytic activity for the oxidation of formaldehyde and hydrazine.(2) Pt/Graphene catalysts were synthesized with a freeze drying / vapor reduction method. Pt clusters with 20-40 nm in size were composed of very fine nanoparticles. The electrocatalytic activity and stability of the catalysts for the oxidation of methanol were investigated. The results indicated that Pt/Graphene catalysis showed excellent electrocatalytic activity and stability for the oxidation of methanol.(3) Ag-Pt/Graphene and Ag-Au/Graphene hollow alloyed catalysis were prepared by a galvanic-replacement reaction. The electrocatalytic activity of the catalysts for the oxidation of methanol was investigated. The results indicated that Ag-Pt/Graphene catalysis showed excellent electrocatalytic activity for the oxidation of methanol while Ag-Au/Graphene catalysis showed poor electrocatalytic activity.Innovations of this dissertation: 1. Ag/Graphene catalysts were synthesized with a freeze drying / vapor reduction method. The catalysts showed excellent electrocatalytic activity for the oxidation of formaldehyde and hydrazine. 2. Ag-Pt/Graphene and Ag-Au/Graphene hollow alloyed catalysis were prepared by a galvanic-replacement reaction. Ag-Pt/Graphene hollow alloyed catalysis showed excellent electrocatalytic activity for the oxidation of methanol.