No abstract

No abstract

No abstract

One of the barriers to the large-scale commercialization of proton exchange membrane fuel cells (PEMFCs) is the high-priced of noble metals such as platinum (Pt). Therefore, in this paper, bimetallic electrocatalyst FeCo supported nitrogen-doped reduced graphene oxide (FeCo-NG) for oxygen reduction reaction (ORR) is proposed and has been successfully prepared through annealing of a mixture containing Fe, Co salts, dicyandiamide (DCDA) and graphene oxide (GO). The starting material GO appeared to be in multilayer sheets through scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis. Due to the high annealing temperature and the absence of the surfactant, agglomeration of FeCo nanoparticles was observed from the morphology analysis. The macrostructure size of the metals particles was observed to be increased over temperature. As the temperature increases, the agglomeration gets more intense because of the increased of van der Waals cohesive forces between the nanoparticles. In addition, the weak electrostatic interaction between the metal cations with the nitrogen and the GO sheets could also be the cause of the agglomeration. The weak electrostatic interaction caused the nanoparticles (Fe and Co) not attracted onto the GO sheets thus inhibit the reduction of FeCo and GO to occur in situ simultaneously. It is believed that the agglomeration of the electrocatalyst FeCo-NG could results to poor electrocatalytic activity of PEMFC.

In this study, graphene oxide (GO) as nano sized filler to improve the properties of polymer electrolyte membrane was synthesized via the modified Hummers method. Hummers is the most common method used to synthesize GO. The GO is produced by exfoliation of graphite oxide under sonication method. Dispersion by sonication method shows mechanical disruption that breaks apart the graphite flakes which is then sterically stabilized in the base solution. The as-synthesized GO will be sulfonated using different precursors, namely (3-mercaptopropyl)trimethoxysilane (MPTMS), butane sultone (BS) and sulfanilic acid (SA). The structure and morphology of GO and sulfonated GO (SGO) were investigated in details by using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). FTIR analysis confirmed the presence of several functional groups such as hydroxyl, epoxy, carbonyl, carboxyl and sulfonic acid group. The obtained SEM and TEM images indicated, that the morphology of GO dispersion is folded, multilayered and crumpled with some wrinkles. The morphology of SGO showed a folded, thicker and overlap surface compared with GO sheets. Based on TEM image, the addition of sulfonic acid group into the GO network reveals the black spot on the sheets surface. This SGO will act as a potential base material for the application of solid acid catalyst, water purification as well as a composite in membrane fabrication.