Enhancement of performance of pyridine modified polybenzimidazole fuel cell membranes using zirconium oxide nanoclusters and optimized phosphoric acid doping level

Nanocomposite proton conducting membranes incorporating zirconium oxide (ZrO2) nanoclusters into solution cast 2,6-pyridine polybenzimidazole (2,6-Py-PBI) films and doped with phosphoric acid (PA) were prepared. The content of ZrO2 nanoclusters in the membrane matrix was varied from 0 to 10 wt%. The parameters of the acid doping reaction were optimized by the response surface method (RSM). The membrane properties were evaluated by Fourier transform infrared (FTIR), scanning transmission electron microscopy (STEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), universal mechanical tester and DC impedance. The incorporation of 5 wt% ZrO2 nanoclusters increased the acid doping level and remarkably enhanced the proton conductivity of the membrane. A maximum proton conductivity of 60.0 mS/cm was recorded compared to 21.5 and 12.0 mS/cm for pristine and 10 wt% ZrO2 containing membranes at 150 degrees C and dry condition, respectively. The membrane with 5 wt% ZrO2 also showed the highest performance in a single cell at 120 degrees C under dry conditions. The results suggest that the composite membrane containing 5 wt% ZrO2 nanoclusters has a potential for application in high temperature proton exchange membrane fuel cell application. Copyright (C) 2016, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.