Nafion® based hybrid composite membrane containing GO and dihydrogen phosphate functionalized ionic liquid for high temperature polymer electrolyte membrane fuel cell

A new hybrid composite proton exchange membrane has been synthesized from dihydrogen phosphate functionalized imidazolium ionic liquid (IL-H2PO4), graphene oxide, and Nafion 117 solution. The chemical structure and thermal stability of the dihydrogen phosphate functionalized imidazolium ionic liquid (IL-H2PO4) have been analyzed by 1H nuclear magnetic resonance (NMR) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric analysis (TGA). The structural, thermal, and surface properties of synthesized membranes have been confirmed by FTIR spectroscopy, X-ray diffraction, TGA, and scanning electron microscopy. The proton exchange membranes have been characterized by their ionic conductivity and unit cell performance. The incorporation of IL-H2PO4 and graphene oxide in the Nafion membrane increases its thermal stability. The ionic conductivity of the membranes increases with temperature and amount of IL-H2PO4. The highest ionic conductivity of 0.061 Scm−1 has been achieved at 110 °C under anhydrous conditions which is 1.3 times higher than that of commercial Nafion 117. The synthesized membrane, Nafion/IL/GO, shows the best unit cell performance with a power density of 0.02 W cm−2, which is 13 times higher than that of the commercial Nafion 117 membrane at 110 °C.