Performance and Durability of Pt-Ni Catalysts Supported on Polypyrrole-Carbon for Fuel Cells

Abstract

Proton exchange membrane fuel cells are environmentally friendly energy conversion systems, but their performance is hampered by poor activity and durability of the catalyst. In the work presented herein, a PtNi catalyst supported on polypyrrole-carbon (PPy-C) was prepared using an electrochemical technique. The molecular structure of the PPy was analyzed by Fourier-transform infrared spectrometry. The surface morphology and structure of the catalysts were characterized by scanning electron microscopy and transmission electron microscopy. Cell polarization curves and impedance spectra showed that PtNi/PPy-C exhibited higher catalytic activity, which can be ascribed to the small size and uniform distribution of the PtNi nanoparticles. Linear sweep voltammetry measurements on a rotating disk electrode indicated that the oxygen reduction reaction kinetics on the surface of PtNi/PPy-C mainly followed a four-electron transfer pathway. The degradation of the performance of PtNi/PPy-C was slower than that of commercial Pt/C in accelerated durability testing. The weakened agglomeration effect during long-term operation is attributed to the corrosion resistance of the PPy carrier with high electrical conductivity. The composite carrier enhanced the catalytic activity and durability of the PtNi/PPy-C.