Fabrication of the cross-linked PVA/TiO₂/C nanocomposite membrane for alkaline direct methanol fuel cells

A crosslinked Poly(vinyl alcohol) based composite membrane was developed through a phase inversion process for use in alkaline direct methanol fuel cells (ADMFCs). The titanium dioxide (TiO₂) and carbon nanoparticles (NPs) have been incorporated into the PVA polymer matrix to improve the mechanical and thermal properties. The membrane samples were further modified with maleic acid, a carboxylic acid acting as the cross-linker, under controlled temperature and time conditions to enhance electrochemical properties. The mechanical strength and thermal stability of membranes were determined using a Universal testing machine (UTM) and thermogravimetric analysis (TGA), while the crystallographic and morphological features were examined through X-ray diffraction (XRD) and Scanning electron microscopy (SEM), respectively. The proton conductivity (σ), methanol permeability, and water uptake (%) were also assessed. The XRD curves, SEM images, and TGA trends confirmed the successful cross-linking of maleic acid, uniform dispersion of nanoparticles (NPs), and excellent thermal stability in the crosslinked PVA-TiO₂-C membrane. This sample also exhibited the highest tensile strength (163 MPa), and lower permeability (45000 Ss/cm³). Moreover, the ionic conductivity was obtained in the order of 10⁻² S/cm. These combined characteristics position the cross-linked PVA-TiO₂-C membrane as a promising candidate for application in alkaline direct methanol fuel cells (ADMFCs).