Polarization losses under dynamic load cycle using multiwall carbon nanotube supported Pt catalyst in PEM fuel cell

Abstract

Durability is one of the most important issues that are still being a hindrance for commercialization of polymer electrolyte membrane fuel cell (PEMFC). In this study, the degradation of PEMFC using multiwall carbon nanotube supported Pt catalyst (Pt/CNT) was investigated under dynamic load cycle procedure. The degradation was characterized by current density-voltage curves, cross-sectional scanning electron microscopy (SEM) images, and Fourier transforms infrared spectroscopy (FTIR) spectra. The load-cycle procedure was carried out for 50 cycles, where one cycle consisted of three steps (OCV–load current–constant voltage). An analysis of cell overpotentials indicated that the predominant source of performance degradation was due to ohmic losses, especially significant increase in the area specific resistance (Ra). After 50 cycles, Ra was calculated three times higher than that before durability test, from 0.67 to 1.74 Ωcm2. Based on the results from SEM images and FTIR spectra, there was no evidence of membrane degradation or thinning. Noticeable degradation was only observed from the increase in the interface gap between membrane, catalyst layer, and gas diffusion layer.