| As the worldwide primary energy, the gap of oil supply is expanding. The developing of new energy is very urgent. Direct methanol fuel cell use methanol as the source of energy and can quickly start in low temperature. Besides of that, DMFC is environmentally and the structure is simple. But the cost and utilization of anode catalyst limits its commercial applications. Platinum as the main material of the anode catalyst is easily affected by the intermediate product, and the noble metal Pt is very expensive. Instead of pure Pt, The catalytic activity of Fe3O4@Pt is improved a lot. In the work, Fe3O4 was prepared by solvothermal method in the size of 100-200nm. The affect of temperature and reaction time to crystallinity, partical size distribution and morphology was studied by TEM and XRD. The amination ofFe3O4 was by 3-aminopropyl triethoxysilane(APTES) to promote the coating of Pt nanoparticles. And the physical characteristics of Fe3O4@Pt was measured by TEM, EDS, XPS and XRD.The electrochemical characteristics was measured by cyclic voltammetry. To further enhance the catalytic activity the Vulcan XC-72R was as the support to prepare Fe3O4@Pt/C composites. The characterization methods was same to that of Fe3O4@Pt. Because Pt can also catalytic the reduction of p-nitrophenol, so the graphene oxide(GO) was as the carrier to prepare Fe3O4@Pt/GO for the nitrophenol reduction catalyst. The physical characteristics and catalytic properties was characterized by TEM and UV-Vis. Here is the conclusion:1) The particle size of Fe3O4 increases with the increasing of temperature and the particle size distribution prone to the narrow width as the extending of reaction time.The degree of crystallinity increase as the temperature became higher. Considering to all the conditions, we choose 200℃-8h to be the optimal condition.2) The molar ratio of Fe3O4@Pt was selected to be 1:1,2:1,3:1 and 4:1 four conditions in the preparation of Fe3O4@Pt. In the condition of 2:1, Pt nanoparticles was completely coated with Fe3O4 core; In the condition of 1:1 there is some independent nucleation Pt nanoparticles. When the molar ratio is 3:1 the Pt nanoparticles were not completely coated Fe3O4 core. Take the cost into account the molar ratio 2:1 is optimum condition. Fe3O44@Pt has excellent stability(the mass activity after 100 cycles compared with the first cycle decreased by 27.3%, and it is mainly because of the methanol consumption), and the catalytic activity is higher than that of pure Pt.3) The load of Fe3O4@Pt/C was 20%. The TEM result shows that Fe3O4@Pt composite particles dispersed in the carbon black surface. The current density of Fe3O4@Pt/C decreased 42.4% compared to the Fe3O4@Pt’s first cycle. And as the reaction time extend, Fe3O4@Pt/C is the same state after 500s.Fe3O4@Pt has a reduced after 1750s.4) The load of Fe3O4@Pt/GO was 50%. Fe3O4@Pt uniformly distributed on the GO surface, and due to the presence of oxygen functional groups, the dispersion of Fe3O4@Pt increases. The UV-vis result shows that the UV absorption intensity of nitrophenol continue to decrease, and a new absorption peak of aminophenol show at around 300nm. Fe3O4@Pt/GO complete the majority of the reduction of nitrophenol in short time. Fe3O4@Pt/GO has a strong role in promoting. |
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