The replacement of the platinum in the active layer of Fuel cells is one of the major issues that prevent the commercial use of proton exchange membrane fuel cells. As an alternative, the literature on the replacement of platinum by tungsten carbide is very ambiguous, and can either show little activity, or promising performances. Our goal in this study was to precisely control the preparation of WC and α-W_2C nanoparticles on the surface of a carbon support. As a support, we have studied a Carbon-Carbon composite material derived from expanded graphite, which will be compared to a more common commercial carbon black. Preparation of supported tungsten monocarbide nanoparticles of a size inferior to 10 nm is not a trivial task. The method investigated in this work uses tungsten chloride WCl_6 as a precursor instead of wolframite or tungsten oxide. Impregnation of the support by WCl_6 is performed by chemical vapour transport, followed by reduction and carburization. Well-dispersed W_2C nanoparticles are obtained at 850°C, while the obtention of WC requires a higher temperature. Potential of W_2C and WC as a replacement for platinum nanoparticles have been evaluated, and results have been compared to platinum nanoparticles deposited on the composite support and on the commercial black carbon Vulcan XC-72R. Our study presents the different preparations routes employed for the electrocatalyst synthesis and the characterisations of the resultant materials using electronic microscopy (SEM, HR-TEM), X-ray diffraction, and elemental analysis as well as electrochemical characterisations.
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