| Summary: | The aim of this project was to develop a new preparative route leading to the synthesis of bimetallic precious metal catalysts to be used in, the anode of fuel cells. These catalysts required high metal dispersion and good interaction between the metals used. Control over high metal loading onto the support was also desirable. / Current preparative methods in industry involve the eo-precipitation of mixed metal oxides onto supports together with subsequent high temperatures treatments to achieve the desired bimetallic structure. The final catalysts generally present agglomeration and segregation of the metals when high loadings are required and high temperature applied. As a result, they show poor surface area and low activity. The method studied in this project consisted of two steps: the preparation of mixed metal oxides nanoparticles stabilised by surfactants and the solution reduction of these species under H2. Both the oxide and reduced particles can be isolated in a powder form and easily re-dispersed into an appropriate solvent to give stable dispersions. The oxide and reduced nanoparticles were absorbed onto carbon supports. Using this method, PtRu catalysts for fuel cell applications were prepared. Cyclic voltammetry was used to determine the surface area of the metal particles onto supports and also gave an indication of surface compositions. Preparative variables were investigated in order to manipulate the characteristics of the particles obtained. Firstly, the nature of the stabiliser was examined, showing that the use of a non-ionic stabiliser yielded high dispersions and narrow size distribution. However, the presence of stabiliser in the final products proved to be an issue for their use as catalysts and a firing stage was then introduced. The resulting catalysts showed higher surface areas than their equivalent standard catalysts but surprisingly performance was not increased. Additionally, it was found that no particle growth was observed at high loading; for instance, good dispersion and high surface areas were still obtained at 60wt% metal onto carbon.
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