Controlled Growth And Electrochemical Properties Of Graphene Based Nanocomposite Structures

Direct methanol fuel cell should have a broad application prospect in the field of energy conversion in the future because of its simple structure and clean fuels. However, since the electrode materials contain a noble metal Pt, which is expensive, so that it is difficult to realize commercialization. To this end, this paper selected graphene as the substrate which has a good conductive property and a larger surface area. Build rGO/WO3 nanostructures through loading WO3 nanorods on the surface of graphene with the coupling effect between graphene and WO3 nanorods. Nitrogen doping was followed to improve the electronic structure of rGO/WO3 nanostructures. Modifying a small amount of Pt particles onto rGO/WO3 nanostructures was also necessary. The electrochemical catalytic properties of catalytic electrode at low loadings of platinum case were studied at last. The main results are as follows:(1) Graphene oxide with 2-3 layers was prepared by an improved Hummers method, and its surface contained a lot of oxygen-containing functional groups, which provided a large number of nucleation sites for WO3 and Pt particles.(2) rGO/WO3 composites were synthesized by hydrothermal method. The controlled preparation of rGO/WO3 composites were achieved by changing the temperature and time. Finally it was found that the optimal experimental parameters is under 180℃ for 28 h. Under these conditions, WO3 exhibits the elongated and smooth nanorods, which is in a length of about 1 μm and a diameter of several tens of nanometers to about 100 nm.(3) NG/Wo.62(N,O) composites were obtained by nitrogen doping of rGO/WO3 composites with an ammonia fumed method. The phase and morphology of composites were controlled by changing the nitriding temperature. The final results are that when the optimal parameter is 800℃, the composite is a single phase of Wo.62(N,O) loading on NG, and the whole morphology is nanorods structure, while the partial collapse of the nanorods occurs. Nitrogen doping amount was controlled by changing the NH3 flow.(4) Precious metal Pt particles was modified on NG/W0.62(N,O) by wet chemical method, in which the diameter of Pt particles was 2-5 nm, and dispersed uniformly. The results were concluded by studying NG/W0.62(N,O)/Pt catalytic oxidation of methanol that:Compared with commercial C/Pt electrode, NG/Wo.62(N,O)/Pt has better electrical catalytic activity and stability. This is because NG has good electrical conductivity. Besides, coupling effects are existed between NG, Wo.62(N,O) and Pt.