Fig. 4. Electrochemical activities of Dair–PtPdCu9, DN2–PtPdCu9 and commercial Pt/C catalysts. (a) ORR polarization curves in O2-saturated 0.1 M HClO4 solution with a sweep rate of 20 mV s–1 and a rotation rate of 1600 rpm. (b) Specific activity and mass activity of these three catalysts. Comparison of ECSAs (c) and mass activities (d) for the catalysts before and after durability testing.
