Catalyst impact on membrane life was examined using inductively coupled plasma spectroscopy, hydrogen peroxide soak, and open-circuit decay. The catalysts PtFe/C and PtNi/C were found to leach ϳ2ϫ less platinum than Pt/C. Nafion in hydrogen peroxide with Ni 2+ emitted ϳ100ϫ less fluoride than with Fe 2+ . At open circuit, Nafion 111 was found to fail at ϳ115, 315, and 520 h with PtFe/C, Pt/C, and PtNi/C cathodes, respectively, at 90°C. It is hypothesized that if the leached cation does not directly impact the membrane decay, e.g., a "poor Fenton reagent," then other cations such as dissolved platinum ions may become critical.
The ORR catalyst for PEMFC needs to be improved in terms of catalytic activity, stability, and reduction of Pt loading to be viable for fuel cell vehicle applications. A drawback of state-of-the-art dispersed platinum nanoparticles on carbon is the corrosion of carbon in the PEMFC vehicle under operation conditions, which also exacerbates the agglomeration of Pt nano-particles. This results in a limited life of the vehicular fuel cell. Conductive metal oxide supported Pt-based ORR catalysts nanoparticles have been studied extensively and showed improved electrochemical stability and catalytic activity through d-band interaction [1,2,3]. However, crystalline conductive metal oxides such as NbO and NbO 2 are not stable in the fuel cell [1]. This work uses a carbon-supported amorphous conductive metal oxide as Pt-based catalyst support for ORR in PEMFC. Amorphous conductive metal oxides have neither grain boundaries, nor the long-range atomic order to be easily transformed into insulating crystalline structure, i.e. amorphous conductive metal oxides are resistant to oxygen incorporation, thus preserving the structural stability and electric conductivity.
A two dimensional (2D) platinum network catalyst on graphitic carbon and amorphous NbO x hybrid support has been synthesized by the Arc Plasma Deposition (APD) method. The 2D platinum structure on the conductive, corrosion resistant amorphous metal oxide significantly increases the catalyst stability under RDE accelerated stress tests. RDE and 5cm 2 MEA single cell test results show that the catalyst has higher specific and mass activities than those of conventionally prepared platinum on graphitic carbon (Pt/GC) catalyst. The microstructures of the catalyst were characterized by scanning tunneling microscopy (STM).
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