Application And Electro-catalytic Performance Study Of Polyaniline In Direct Methanol Fucel Cell

Direct methanol fuel cell(DMFC) is considered as a prospective power source for a variety of portable devices, due to its high-energy efficiency, the accessibility of fuel, environmentally friendly natureand convenient manipulation over other power sources. However, how to improve the electro-catalytic proformance of anode catalyst is a challenge in the development of DMFC. At present, Pt catalyst is still the most efficient anode catalyst for DMFC. But Pt catalyst has a fatal weakness: it has a low electro-catalytic activity and stability in the process of methanol electro-oxidation. Choosing the suitable catalyst support is an important way to improve the electro-catalytic proformance of Pt catalyst. Our work represents a new type of electro-catalyst with several important benefits, and studies the effect of this electro-catalyst on the improvement of electro-catalytic proformance of Pt catalyst.The hybrid support titania-carbon black(Ti O2-C) is used as catalyst support and functionalized by polyaniline(PANI) to further improve the electro-catalytic activity and stability of platinum/titania-carbon black(Pt/Ti O2-C) for methanol electro-oxidation for the first time. Pt nanoparticles have been successfully assembled on PANI-functionalized Ti O2-C by chemical reduction method in aqueous solutions. First, aniline(An) monomer was selectively adsorbed onto the hybrid support(Ti O2-C) surface and was then polymerized in situ on the surface of hybrid support via ammonium peroxodisulfate(APS) oxidation in sulfuric acid( H2SO4)solution. Subsequently, aqueous reduction processes involving hexachloroplatinic acid and formic acid(HCOOH) are used to deposit Pt nanoparticles on the supports.The electro-catalytic activity and stability of catalysts towards methanol electro-oxidation were characterized by cyclicvoltammetry( CV) and chronoamperometric curves, which show that the electro-catalytic activity and stability of the novel platinum-polyaniline/titania-carbon black(Pt-PANI/Ti O2-C) catalyst are really improved, compared to the Pt/Ti O2-C catalyst. The physical properties of catalysts were studied by Fourier transform infrared spectroscopy(FTIR), X-ray diffraction(XRD), Energy dispersive X-ray spectroscopy(EDS), Transmission electron microscopy(TEM), which indicates that with the PANI functionalization, the Pt nanoparticles are smaller in size and more uniformly dispersed on the surface of Ti O2-C than those of Pt/Ti O2-Ccatalyst. The improved electro-catalytic stability of Pt-PANI/Ti O2-C catalyst can be attributed to the interaction between Pt and PANI, which was demonstrated by X-ray photoelectron spectroscopy(XPS). At the same time, the preparation of Pt-PANI/Ti O2-C catalyst has also been optimized in our work. It is concluded that the best. The conclusion was as follow: it shows that the optimal electro-catalytic activity and stability of the Pt-PANI/Ti O2-C catalyst was achieved when the content of Ti O2 in the hybrid support Ti O2-C was 40%, the dosage of An was 30%, the molar ratio of An to APS was 1:1, and the concentrations of H2SO4 was 1.0 mol L-1.In addition, we also studied the electro-catalytic activity and stability of the Pt-PANI/Ti O2 and Pt-PANI/C catalysts. The conclusion was as follow: when Ti O2 was used as the catalyst support in the Pt-PANI/Ti O2 catalyst, its electro-catalytic activity was lower than that of the Pt-PANI/C catalyst, but its stability was higher than that of the Pt-PANI/C catalyst, in which C was used as the catalyst support.