Synthesis And Performance Of Graphene-Based Catalysts Used In Pemfc Cathode

The valuable platinum is still the main cathode catalyst for proton exchange membranefuel cell（PEMFC）, which is one of the reasons that cause the high cost of PEMFC. Also, thehigh cost greatly limits the widely application of PEMFC. So, the amount reducing of noblemetal catalyst, the low-cost catalyst finding and the utilization enhancing of the catalyst arethe main objects of catalyst research. The main content of the thesis is about the preparationof a proton exchange membrane fuel cell cathode catalyst. The cathode catalyst is expected toreplace the platinum-based precious metal catalysts. The main conclusions are as follows:（1）In this study, we report a facile method to prepare a Fe-N-C catalyst based onmodified graphene （Fe-N-rGO） from heat treatment of a mixture of Fe salt, ammoniumcarbamate or imidazole, and chemically reduced graphene （rGO）.（2）The surface chemical composition of Fe-N-rGO is examined by X-ray photoelectronspectroscopy （XPS）. Scanning electron microscope（SEM）, Transmission electron microscopy（TEM） and X-ray diffraction（XRD） were used to characterize these catalysts in terms of theirstructure and morphology. To assess catalyst ORR activity, line-scan voltammetry（LSV） andcyclic voltammetry （CV） using RDE technique were carried out.（3）The catalyst has good catalytic activity when the nitrogen source is ammoniumcarbamate; and the catalyst is evaluated by the following indicators. Fe-N-rGO shows bestelectrocatalysts capability when heat treat at850℃; Compared Cat_maxwith20%Pt/C, theoriginal reduction potential was approximately positive80mV than20%Pt/C, but the numberof electrons transferred per oxygen molecule were3.86, similarly with20%Pt/C, thisindicates that almost all the oxygen molecule was reduced to water; The oxygen reductioncurves with or without methanol showed that methanol has no effect with the oxygenreduction reaction. So the Fe-N-rGO/NH₃catalyst was methanol-tolerant.