Ethanol in direct liquid fuel cells is an almost ideal source for sustainable energy. Efficient electrocatalytic material research for its oxidation has to deal with a complicated reaction mechanism, i.e. the need for C-C bond breaking. High activity and selectivity are both desired in unison while avoiding poisoning effects due to possible organic byproducts. In order to address this problems of incomplete oxidation of ethanol efforts to develop highly active and selective electrocatalysts have been focused on the addition of co-catalysts to platinum. The overall objective of this thesis was to develop new highly active electrocatalytical concepts for the ethanol oxidation reaction in acidic and alkaline media, while emphasizing on synthesis-activity relations and selectivity investigations. To achieve this, platinum and rhodium have been combined with either tin or nickel, aiming for novel ternary single phased nanocatalysts with enhanced electrocatalytic surface properties in order to successfully adsorb ethanol, facilitate the intermolecular bond break and supply active oxygen-containing species for the complete oxidation at the same time. Their activity was matched to changes in composition, morphology, bulk and surface structure and synthetic route influences. Subsequently, the corresponding selectivity of the electrocatalytic concepts was investigated with an optimized custom build in situ FTIR cell setup. In contrast to other in situ FTIR setups, the electrochemical current responses inside the FTIR setup reported here were similar to standard electrochemical measurements and showed little to no mass transport limitation within the measuring requirements. In situ FTIR spectra of adsorbed species on the catalyst film as well as features from the electrolyte over the catalyst film could be detected and correlated to species involved in the electrocatalytic oxidation of ethanol. In summary, this work determined that a higher order of a shape-controlled ternary bulk structure results in higher concentrations of active surface site ensembles consisting of all three metals. Their activity outperformed previously reported comparable catalytic systems in both acidic and alkaline media and hold the possibility to oxidize ethanol and break the C-C bond easily at early onset potentials nearly as low as the reversible potential.


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    Titel :

    In situ FTIR studies on nanoscaled electrocatalysts for the ethanol oxidation in direct liquid fuel cells


    Weitere Titelangaben:

    In-situ FTIR Untersuchungen an nanoskaligen Elektrokatalysatoren zur Ethanol-Oxidation in Flüssigbrennstoffzellen


    Beteiligte:

    Erscheinungsdatum :

    2016



    Medientyp :

    Sonstige


    Format :

    Elektronische Ressource


    Sprache :

    Englisch



    Klassifikation :

    DDC:    629 / 541