Development of functionalized nanocomposite membrane composed of sulfonated PVDF/GO and thermo-mechanically modified Fly-Ash for application in PEMFCs

Polymer electrolyte membrane fuel cells (PEMFCs) have become a promising technology due to their high efficiency and zero emission of toxic gases. The present work deals with the fabrication of a cost-efficient nanocomposite proton exchange membrane (PEM), prepared by incorporation of graphene oxide (GO) prepared in the laboratory by modified Hummer's method and thermo-mechanically modified Fly Ash (FA) within the host PVDF [poly(vinylidene fluoride)] polymer matrix. Subsequently, the nanocomposite membranes were treated with the well-known sulfonating agent chlorosulfonic acid at 60 °C for 30 min. The incorporation of GO and FA nanoparticles into the polymer matrix and the membrane sulfonation was verified using various spectroscopic methods, including XRD, FTIR, Laser Raman, FESEM-EDX, and AFM analyses. The highest ion exchange capacity (IEC) and proton conductivity (PC) are observed to be 0.88 meq g⁻¹ and 4.08 × 10⁻² S/cm respectively for the fabricated membrane SPGF-3. Further, it was interesting to note that with an increase in temperature from 25 °C to 75 °C, the fabricated membrane (SPGF-3) exhibited enhanced water uptake capacity from 25.6 % to 30.6 % respectively. The fuel cell performance test showed that the sulfonated membrane, composed of 95 wt% PVDF, 2.5 wt% GO, and 2.5 wt% FA, achieved a maximum current density of 1000 mA cm⁻² and a power density of 448 mW cm⁻² which quantifies its potency towards an alternative to costly Nafion membranes for PEMFCs application.