Department of Chemistry and Polymer Science

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Browsing Department of Chemistry and Polymer Science by browse.metadata.advisor "Bessarabov, D. G."

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    Microheterogeneous solid polymer electrolyte (SPE) membranes for electrocatalysis
    (Stellenbosch : Stellenbosch University, 2002-04) Michaels, W. C.; Bessarabov, D. G.; Sanderson, R. D.; Stellenbosch University. Faculty of Science. Dept. of Chemistry and Polymer Sciences.
    ENGLISH ABSTRACT: The deposition of platinum catalyst on cation-exchange membranes was achieved by a counter diffusion deposition method known as the Takenaka- Torikai method. The morphology of the platinum catalyst on the membranes were controlled by varying the conditions of the platinum deposition process, such as, temperature, type of reducing agent and concentration of the platinic acid solution. The effect of the sonication of platinic acid solution and the pre-treatment of membranes on the morphology of a platinum catalyst was also investigated. Platinum loading on cation-exchange membranes was determined by UV spectrophotometric and gravimetric analyses. Suitable conditions for the quantitative determination of the platinum loading on membranes by UV spectrophotometric analysis was established through the development of a protocol. Membranes were characterised using different techniques such as, Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), Infrared spectrometry (IR), Dielectric analysis (DEA) and Brunauer Emmett Teller adsorption (BET). The roughness profile of a platinum catalyst embedded on a membrane was explored by various statistical methods. The statistical analysis of various data sets for a surface of a platinum-containing membrane was investigated using the Hurst exponent. The effect of surface modification of membranes on the deposition process, as well as the morphology of the platinum catalyst, was investigated. Membranes were modified with ethylene diamine (EDA) and cetyltrimethylammonium bromide surfactant. Modification of membranes with cetyltrimethylammonium bromide surfactant resulted in a unique textured platinum catalyst. The electrochemical "switching" phenomenon was investigated for EDAmodified membranes and EDA-modified membranes embedded with platinum catalyst. The "switching" phenomenon was observed in i-V cyclic curves, which were obtained by galvanodynamie measurements. The application of electro catalytic membrane systems in the anodic oxidation of water was investigated by electrochemical techniques such as galvanostatic and cyclic voltammetric measurements.