Kinetics of hydrogen oxidation (HOR) and hydrogen evolution (HER) reactions on nanostructured thin-film (NSTF) ternary Pt0.68Co0.3Mn0.02 catalyst was investigated in a 50-cm2 polymer electrolyte fuel cell operated in H2 pump mode with supersaturated feeds at 45–90°C and 0.7–2.5 atm H2 partial pressures. The results showed that the HOR and HER are completely reversible, and that both of these reactions can be described by the same Butler-Volmer kinetics with first-order dependence on the H2 partial pressure. The specific exchange current density for the 2-electron HOR/HER on the NSTF ternary catalyst, derived from the measured polarization curves, is 489 mA.cmPt−2 at 80°C and 1-atm H2 partial pressure. The temperature dependence of the exchange current density is consistent with an activation energy of 38.9 kJ.mol−1. Compared to dispersed Pt/C catalyst with an ultralow 0.003 mg.cm−2 Pt loading, the HOR kinetics on NSTF catalyst with 0.05–0.10 mg.cm−2 Pt loading was 60–110% faster on an area-specific basis, but it was slower on a mass basis. The measured HOR/HER kinetics is a function of the state of the catalyst in that the specific exchange current density increased by 460% when the anode catalyst was conditioned with the same protocol normally used for the cathode catalyst.
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Wang et al. (2013) studied this question.