Enhancing the Performance of Poly(phthalazinone ether ketone)-Based Membranes Using a New Type of Functionalized TiO2 with Superior Proton Conductivity

A novel, high-efficiency, and cost-effective series of sulfonated poly(phthalazinone ether ketone)/sulfonated titanium dioxide@toluene diisocyanate@ethylenediamine (SO3H−TiO2@TDI@EN-SO3H) nanocomposite membranes is designed to enhance the proton conductivity and methanol barrier of the proton exchange membrane (PEM). The nanocomposite membranes were prepared via a facile one-step process of the solution casting method. The presence of organic–inorganic SO3H–TiO2@TDI@EN-SO3H nanoparticles improved the performance of the nanocomposite membranes in terms of mechanical stability, proton conductivity, methanol permeability, and selectivity. We used toluene diisocyanate (TDI) as a linker to exploit the properties of sulfonated TiO2 and sulfonated ethylenediamine (EN-SO3H) nanoparticles. These nanoparticles act as Lewis and Brønsted acids simultaneously because of the presence of sulfonamide, TiO2, and SO3H groups, which increase the kinetics of the reaction between the membrane and electrode, improving the performance of the direct methanol fuel cell (DMFC). The DMFC, which is assembled using the nanocomposite membrane with 5 wt % SO3H–TiO2@TDI@EN-SO3H nanoparticle (MSN5) membrane, exhibited a maximum power density of 59.22 mW cm–2 during testing because of high proton conductivity and low methanol permeability. The MSN5 membrane is a promising PEM for DMFCs.