Activity, Structure and Degradation of Dealloyed PtNi₃Nanoparticle Electrocatalyst for the Oxygen Reduction Reaction in PEMFC

We report a synthesis, activity and stability study of a dealloyed, highly active PtNi 3 alloy nanoparticle catalyst for the oxygen reduction reaction (ORR) in acidic media. After activation by electrochemical dealloying of a PtNi 3 precursor, the Pt-Ni nanoparticle catalyst (referred to as "dealloyed PtNi 3 ") exhibits a 7–8 times higher Pt mass based activity and a 6–7 times higher Pt surface area specific based activity for ORR than pure Pt at comparable mean particle size. In addition, the long-term stability of the dealloyed PtNi 3 was tested for typical fuel cell operating as well as more corrosive fuel cell start-up conditions. After 10000 voltage cycles between 0.5–1.0 V vs. RHE at 50 mV s −1 the dealloyed PtNi 3 catalyst still shows 4–5 fold increase in Pt surface area specific based activity compared with that for pure Pt.