Hybrid Electrocatalysts for Degradation Mitigation in PEFCs

摘要

Pt/C/MnO_2 hybrid catalysts were prepared by a wet chemical method. Rotating ring-disk electrode (RRDE) experiments were performed to estimate the amount of hydrogen peroxide (H_2O_2) formed during the oxygen reduction reaction (ORR) as a function of MnO_2 content. Pt/C/ MnO_2 (5% by weight of MnO_2) hybrid electrocatalysts produced 50% less hydrogen peroxide than the baseline Pt/C electrocatalyst. The hybrid electrocatalysts were used to prepare membrane electrode assemblies that were tested at 90℃ and 50% RH at open circuit with pure hydrogen as fuel and air as the oxidant. The concentration of F" in the anode condensate over 24 hours was found to be reduced by a factor of 3-4 when Pt/C/MnO_2 replaced Pt/C as the catalyst. Through cyclic voltammetry and RRDE kinetic studies, the lower ORR activity of the hybrid electrocatalysts was attributed to catalyst treatment with acid during MnO_2 introduction.