Synthesis And Electrochemical Properties Of Non-Pt Catalysts In Fuel Cells

Energy is an essential basis for development of human society. With the progress of the society, consumption of the fossil energies produced a series of environmental problems, which strongly hinder the development of economy. Therefore, it is highly desirable to search for green energies with the features of3E (Economy, Energy, Environment). Recently, fuel cells have been attracted considerable interest because of various advantages, including high power density, zero or low exhaust, ease of recharging, simple structure, quick startup at low temperature, direct conversion of chemical energy to electrical energy with high efficiency. Therefore, the fuel cells are considered as a green energy.Currently, Pt and PtM/C electrocatalysts are widely used in fuel cells for various electrocatalytic reactions:the anode oxidation in alcohols fuel cell; the anode and the cathode in hydrogen fuel cell and preparation of hydrogen in hydrogen evolution reaction (HER), the cathode oxygen reduction reaction (ORR) in fuel cell. Due to the limitation of Pt in the world and deactivation of the Pt catalysts, the wide applications of Pt-based fuel cells are very difficult currently. Therefore, it is desirable to develop the highly efficient non-Pt electrocatalysts. This paper is devoted to the synthesis of non-Pt electrocatalysts in fuel cells.Firstly, organotemplate-free synthesis of aluminum-rich Beta zeolite (Beta-SDS) was performed using conventional Beta crystals as seeds synthesized in the presence of organic template, TEAOH (Beta-TEA). Nickel form of Beta zeolite was prepared from ion-exchange of sodium with nickel cations. Because of aluminum-rich Beta-SDS (Ni2+), the Ni-Beta-SDS have more nickel cations than the Beta-TEA zeolite. The cyclic voltammograms and chronoamperograms measurements show that the Ni-Beta-SDS electrode exihibits enhanced electrocatalytic activity performance of methanol oxidation reaction (MOR) in alkaline solution, compared with the Ni-Beta-TEA electrode.Secondly, the urchin-like spinel NiCO2O4crystals were hydrothermally synthesized without using templates. The cyclic voltammetry and chronoamperometry measurements shows that the NiCO2O4electrode gives good electrocatalytic activity of MOR in alkaline solution, compared with the metal oxide, nickel oxide (NiO), and the cobalt oxide (CO3O4). The order of activity and stability is as follows:urchin-like NiCo2O4> NiO> CO3O4.Thirdly, nanosheet molybdenum disulfide (MoS2) was successfully synthesized in the presence of ammonium fluoride (NH4F). The hydrogen evolution reaction (HER) tests in sulfuric acid solution show that the nanosheet MoS2exihibits better electrocatalytic activity than the bulk MoS2synthesized in the absence of NH4F, which is due to that the nanosheet MoS2has more active sites.Finally, the nitrogen-doped graphene (N-Graphene) was synthesized from a mixture of polyhexamethylene biguanidine hydrochloride (PHMB) and graphene oxide (GO). The as-synthesized N-graphene materials exihibit good electrocatalytic activity for oxygen reduction reaction in the alkaline solution with the number of electron transfer is closed to4.