Abstract:

By using pulse-microwave assisted chemical reduction, we prepared a Pt-Ni alloy supported on a cobalt-polypyrrole-carbon (Co-PPy-C) catalyst. The catalyst microstructure and morphology were characterized by using transmission electron microscopy (TEM) and X-ray diffraction (XRD). The electrocatalytic performance and durability of the catalysts were measured with cyclic voltammetry (CV) and linear sweep voltammetry (LSV). The metal particles were well dispersed on the carbon support, and the particle size of PtNi/Co-PPy-C was about 1.77 nm. XRD showed that the Pt(111) diffraction peak was strongest, so the most of the Pt in the catalysts was in a face-centered cubic lattice. The electrochemical surface area (ECSA) of PtNi/Co-PPy-C (72.5 m²·g^-1) was higher than that of Pt/C(JM) (56.9 m²·g^-1). After an accelerated durability test for 5000 cycles, the particle size of PtNi/Co-PPy-C obviously increased. The degradation rate of ECSA and the mass activity (MA) of PtNi/Co-PPY-C were 38.2% and 63.9%, respectively. We applied the PtNi/Co-PPy-C catalyst after optimizing the membrane electrode assembly (MEA) with an area of 50 cm². The fuel cell could be suitably operated at 70 ℃ with a back pressure of 50 kPa. At these conditions, the maximum power density of MEA by PtNi/Co-PPy-C was 523 mW·cm^-2. The excellent performance of PtNi/Co-PPy-C makes it a promising catalyst for proton exchange membrane fuel cells (PEMFCs).

Key words: Proton exchange membrane fuel cell, Oxygen reduction reaction, Co-PPy-C, PtNi/Co-PPy-C, Electrochemical activity, Electrochemical stability