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Single-cell and half-cell degradation test procedures were evaluated for carbon-supported Pt/C, PtCo/C and PtNi/C catalysts. Half-cell analyses were employed to understand the effect of the number of cycles and of the scan rate over the cathode catalysts degradation under potential cycling from 0.6 to 1.2 V. The data suggested a time-dependent degradation for all three catalytic systems. Single-cell measurements were used to evaluate the impact of catalyst degradation on fuel cell performance. The measurements in both setups showed similar ECSA and ORR mass activity losses. Specific degradation mechanisms related to Pt dissolution, Pt agglomeration, and transitional metal leaching were quantified and correlated with performance losses.ß 2014 Published by Elsevier Masson SAS on behalf of Acade ´mie des sciences. § Thematic issue dedicated to Franc ¸ois Garin.

Single-cell and half-cell degradation test procedures are evaluated for carbon supported Pt catalysts. Half-cell analyses are employed in identification of specific test parameters for evaluation of cathode catalysts. Single-cell measurements run at 100 % relative humidity (RH) evaluate the impact of catalysts degradation on fuel cell performance. The measurements in both setups show a 20 % deviation of the electrochemical surface area loss (ECSA), while the oxygen reduction reaction (ORR) activity losses were comparable. The quantification of specific degradation mechanism as Pt dissolution and particle agglomeration in correlation with surface area and oxygen reduction activity is discussed.

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.

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