Proton exchange composite membranes from blends of brominated and sulfonated poly(2,6-dimethyl-1,4-phenylene oxide)

Unveiling CeZnOx Bimetallic Oxide: A Promising Material to Develop Composite SPPO Membranes for Enhanced Oxidative Stability and Fuel Cell Performance

The incorporation of cerium-zinc bimetallic oxide (CeZnOx) nanostructures in sulfonated poly(2,6-dimethyl-1,4-phenylene oxide) (SPPO) membranes holds promise in an enhanced and durable fuel cell performance. This investigation delves into the durability and efficiency of SPPO membranes intercalated with CeZnOx nanostructures by varying the filler loading of 1, 2, and 3% (w/w). The successful synthesis of CeZnOx nanostructures by the alkali-aided deposition method is confirmed by wide-angle X-ray diffraction spectroscopy (WAXS), Raman spectroscopy, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) analyses. CeZnOx@SPPO nanocomposite membranes are fabricated using a solution casting method. The intricate interplay of interfacial adhesion and coupling configuration between three-dimensional CeZnOx and sulfonic moieties of the SPPO backbone yields an enhancement in the bound water content within the proton exchange membranes (PEMs). This constructs simultaneously an extensive hydrogen bonding network intertwined with the proton transport channels, thereby elevating the proton conductivity (Km). The orchestrated reversible redox cycling involving Ce3+/Ce4+ enhances the quenching of aggressive radicals, aided by Zn2+, promoting oxygen deficiency and Ce3+ concentration. This synergistic efficacy ultimately translates into composite PEMs characterized by a mere 4% mass loss and a nominal 6% decrease in Km after rigorous exposure to Fenton's solution. Remarkably, an improved power density of 403.2 mW/cm2 and a maximum current density of 1260.6 mA/cm2 were achieved with 2% loading of CeZnOx (SPZ-2) at 75 °C and 100% RH. The fuel cell performance of SPZ-2 is 74% higher than its corresponding pristine SPPO membrane.

H+-Conducting Aromatic Multiblock Copolymer and Blend Membranes and Their Application in PEM Electrolysis

As an alternative to common perfluorosulfonic acid-based polyelectrolytes, we present the synthesis and characterization of proton exchange membranes based on two different concepts: (i) Covalently bound multiblock-co-ionomers with a nanophase-separated structure exhibit tunable properties depending on hydrophilic and hydrophobic components’ ratios. Here, the blocks were synthesized individually via step-growth polycondensation from either partially fluorinated or sulfonated aromatic monomers. (ii) Ionically crosslinked blend membranes of partially fluorinated polybenzimidazole and pyridine side-chain-modified polysulfones combine the hydrophilic component’s high proton conductivities with high mechanical stability established by the hydrophobic components. In addition to the polymer synthesis, membrane preparation, and thorough characterization of the obtained materials, hydrogen permeability is determined using linear sweep voltammetry. Furthermore, initial in situ tests in a PEM electrolysis cell show promising cell performance, which can be increased by optimizing electrodes with regard to binders for the respective membrane material.

High degree sulfonated poly(ether ether ketone) blend with polyvinylidene fluoride as a potential proton-conducting membrane fuel cell

Sulfonated poly(ether ether ketone) (sPEEK) membrane is a promising proton-conducting membrane for fuel cell. However, the performance and lifetime of sPEEK membrane depend on the degree of sulfonation (DS). High DS of sPEEK increases the performance, but the mechanical properties could deteriorate progressively which affect its lifetime. Thus, this study investigated the effect of adding polyvinylidene fluoride (PVDF) into high DS (80%) of sPEEK through solution blending method toward its physicochemical properties and morphology structures. The PVDF concentration was varied to 5, 10, 15, and 20 wt% relative to the sPEEK content. The existence of hydrophobic PVDF in 80% sPEEK improved the mechanical properties where the water uptake and swelling degree of membrane decreased, whereas the tensile strength increased. The sPEEK/PVDF 15 exhibited the highest proton conductivity (46.23 mS cm−1) at 80°C. Incorporating PVDF into high DS of sPEEK enhanced the mechanical properties which can be used as a proton-conducting membrane for fuel cell that may improve the performance and prolong the lifetime of the cell.