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Lookup NU author(s): Dr Balakondareddy SanaORCiD, Dr Simon DohertyORCiD, Professor Mohamed MamloukORCiD
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This study investigates the reinforcement of quaternised styrene-ethylene-propylene-styrene (QSEPS) ionomers using a porous PTFE matrix (1 μm pore size and 70% porosity) and cerium oxide (CeO2) nanoparticles as a strategy to balance mechanical durability, ionic conductivity, and oxidative stability of the anion exchange membrane in a water electrolyser (AEMWE). Vacuum filtration achieved 69 wt.% QSEPS loading in PTFE, with 72.5 wt.% infiltrating pores (60.1 v.% pore occupancy) and 27.5 wt.% forming an 8 μm surface layer. The composite QSEPS/PTFE exhibited reduced ionic conductivity of 0.025 S/cm at 20°C compared with 0.038 S/cm for neat QSEPS, corresponding to a 32% reduction. This has been attributed to geometric constraints and tortuous ion pathways of PTFE alongside limited hydration (16% lower water uptake than QSEPS). Incorporating 6 wt.% CeO2 nanoparticles enhanced oxidative stability via radical scavenging, using the Ce3+/Ce4+ redox cycle to neutralize hydroxyl radicals. Despite a lower initial conductivity (35 mS/cm at 60°C, 73% of QSEPS/PTFE), QSEPS/CeO2/PTFE achieved higher tensile strength (21.04 MPa) and retained 246 mA/cm2 current density after 900 hrs of electrolysis (24.2% higher than QSEPS/PTFE). Solid-state 13C NMR cross-polarization total sideband suppression (CPTOSS) of residual solid membranes and solution 1H and 13C NMR of the residual Fenton solution is consistent with the "two-segment" fragmentation model, which explained post-degradation soluble/insoluble residue formation. Solution 1H and 13C NMR identified identical soluble byproducts in both composites which include carbonyl species such as aldehydes and carboxylates as well as ammonium salts possible resulting from nucleophilic substitution. While CeO2 mitigated backbone oxidation it failed to protect quaternary ammonium (QA) groups, highlighting a trade-off between mechanical reinforcement and QA stability. In other words, CeO2 only mitigates hydroxyl radical flux, which decreased the degradation rate.
Author(s): Mohanraj C, Atout HAE, Sana B, Doherty S, Mamlouck M
Publication type: Article
Publication status: In Press
Journal: International Journal of Hydrogen Energy
Year: 2026
Acceptance date: 12/01/2026
Date deposited: 04/02/2026
ISSN (print): 0360-3199
ISSN (electronic): 1879-3487
Publisher: Elsevier Ltd
URL: https://www.sciencedirect.com/journal/international-journal-of-hydrogen-energy
