Results And Discussion

In-silu X-ray diffraction measurement — Typical in-situ X-ray diffractograms of alloy-electrocatalysts during the anodic polarization are shown in Fig.2. The "as-received" electrocatalysts showed a broad peek around 41.6°, which corresponds to (11 l)-diffraction of Pt [Co • Ni] alloy phase. With increasing the corrosion time, the peak intensity of the original alloy decreased and the another peak intensity at 40.0°, assigned as ¿/(111) of pure-Pt, became stronger. This indicates that the dealioying of electrocatalyst occurred within a few hours at 0.9V at 240°C. Since the shape of the peak became sharp with time, the corrosion process also induced a growth of Pt particles. Thus, the in-situ XRD is very useful to know the time-course of the degradation process of electrocatalysts.

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