Study On The Construction Of Spherical Catalyst And The Application For The Electrooxidation Of Methanol

Direct methanol fuel cell (DMFC) is a reproducible and clean chemical energy that can be converted continuously into electrical energy. With low operating temperature, no electrolyte corrosion, no environmental pollution, high energy efficiency ratio and safe and reliable characteristics, it quickly developed into major international hot spots of high-tech competition. Methanol with wide sources, convenience to carry and store, as a direct source of energy of direct methanol fuel cells, its final product do not pollute environment. But the intermediate product of electro-catalytic oxidation of methanol easily created catalyst poisoning on the electrode material, resulting in degradation of battery performance and shortening of life expectancy. And at present the metal materials, used for researching methanol's electro-oxidation, are mostly limited resources, expensive precious metals and their alloys. Thereby these shortcomings are seriously effecting commercial development of direct methanol fuel cell. In order to improve catalytic ability of catalyst of small organic molecules, capability of anti-CO poisoning, and reduce cost of electrode'production, in the paper we developed our work mainly around this hot issue, which has been dealt in the following parts.1. Electrodeposition of platinum microparticle interface on conducting polymer film modified nichrome for electrocatalytic oxidation of methanolUsing nichrome alloy as substrate electrode, spherical platinum particles polyaniline-modified electrode was prepared by cyclic voltammetry in aniline, K2PtCl6 solution in proper sequence. The morphology and structure of the electrode is observed by scanning electron microscopy (SEM). Electrochemical characteristics and electro-catalytic oxidation of methanol were studied under the existing conditions of H2SO4 by cyclic voltammetry, chronoamperometry and alternating current impedance. The results show that, spherical Pt particles on modified electrodes display good stability enhance the electrocatalytic activity for methanol and anti-poisoning ability for intermediate oxidation products of methanol, greatly. So low-cost spherical platinum particles polyaniline-modified electrode fabricated by this method and experimental procedure, reduces the amount of precious metals and improves the catalytic activity of Pt microparticle, significantly. It is expected to be used as electrode materials for fuel cell. 2. Electrocatalytic oxidation of methanol on spherical Ni particles polyaniline-modified electrode in alkaline mediumBy electrochemical method, spherical Ni particles polyaniline-modified electrode is preparated on nichrome alloy substrate in the solution of aniline monomer with cyclic voltammetry and nickel ions solution with constant-potential electrolysis, successively. The surface features of the electrode are observed by SEM. Electrochemical characteristics and electro-catalytic oxidation of methanol are investigated by cyclic voltammetry, chronoamperometry and alternating current impedance in alkaline medium. Experiments show that spherical particles Ni polyaniline-modified electrode has thoroughly changed the surface structure of polyaniline film modified electrode and nickel particles modified electrode preparated only by the direct deposition of the nickel particles on the matrix electrode. Compared to spherical platinum particles polyaniline-modified electrode, the modified electrode has the same high electrocatalytic activity and good stability, avoiding the consumption of precious metal, reducing the cost of preparation. The modified electrode increases catalytic activity for methanol by embeding the transition metal Ni in the polymer film.3. The effect of surfactants on electrochemical behavior of spherical Ni particles polyaniline-modified electrode for methanolBecause of the use of the anionic surfactant sodium dodecyl benzene sulfonate in the preparation and processing of spherical nickel particles polyaniline-modified electrode, cyclic voltammetry and chronoamperometry are used to investigate the impact on current, potential and anti-poisoning ability of different electrodes producted by using different surfactants in the preparation and processing, such as cationic surfactant dodecyl trimethyl ammonium bromide (DTAB), anionic surfactant sodium dodecyl benzene sulfonate (SDBS) and non-ionic emulsifier OP. Experimental results show that the amount of surfactant have a certain affect on current and potential. Anionic surfactant SDBS and non-ionic emulsifier OP can improve the oxidation peak current, reduce peak potential and improve the anti-poisoning ability. Conversely, the presence of cationic surfactant DTAB hinders oxidation process of methanol.4. Electrocatalytic oxidation for methanol with nickel supported on poly (o-phenylenediamine) film electrode in alkaline mediumNickel supported on poly-o-phenylenediamine film modified nichrome substrate is obtained by electro-polymerization of o-phenylenediamine monomers and potentiostatic electrodeposition of nickel in proper sequence on the matrix of nichrome. The modified electrode is applied to methanol electro-oxidation in alkaline media. SEM was employed to characterize the morphology of electrode surface. The electrochemical properties of Ni/PoPD/Nichrome for methanol were studied by cyclic voltammetry, chronoamperometry and alternating current impedance. The results exhibits that dispersity of nickel particles and the oxidation peak's current of methanol is significantly improved, and the catalytic activity of nickel particles was further enhanced. Under the same experimental conditions, the effects of the polymerizing cyclic times of o-phenylenediamine and the deposit time of nickel particles were also investigated. It is expected that the modified electrode would have been further developed in the practical application of fuel cells. Look forward to the development of practical applications.