Graphene Oxide as a Filler for Improved Conductivity and Mechanical Stability in Poly(co-aryl piperidinium) Anion Exchange Membranes
L. calzolari (TU Delft - Applied Sciences)
D.A. Vermaas – Mentor (TU Delft - ChemE/Transport Phenomena)
H. Bazyar – Mentor (TU Delft - ChemE/Transport Phenomena)
A. Papageorgiou – Mentor (TU Delft - ChemE/Transport Phenomena)
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Abstract
The drive for sustainable hydrogen production has highlighted Anion Exchange Membrane Water Electrolysis (AEMWE) as a promising technology. Operating in alkaline conditions, AEMWE can utilize non-precious metal catalysts, offering a cost-effective alternative to proton exchange membrane (PEM) electrolysis. Achieving industrial scalability for AEMWE, however, depends on enhancing the performance of anion exchange membranes (AEMs), particularly by improving hydroxide ion conductivity, mechanical properties and stability in alkaline media.
This study aims to determine the optimal graphene oxide (GO) concentration as a nanofiller in poly(co aryl piperidinium) AEMs to maximize hydroxide conductivity and dimensional stability. The research followed a two-stage approach: first, developing a reproducible membrane fabrication method to create uniform GO-AEM composites, refining solvent composition, thermal treatment, and mixing techniques. Key improvements, including a 5% water-DMSO co-solvent system, enhanced GO-polymer interactions and stability across GO concentrations.
In the second stage, various GO concentrations were systematically evaluated to identify an optimal loading. Conductivity testing revealed a peak at 0.5% GO, where conductivity nearly doubled from 33 mS/cm in the pristine membrane to 59 mS/cm, attributed to enhanced ion-conducting pathways. Ion exchange capacity (IEC) slightly declined, suggesting GO’s active participation in ion conduction or structural improvement. Electrochemical performance tests demonstrated that membranes with higher conductivity corresponded to improved current densities.
Microscopic and thermal analyses (SEM, AFM,TGA) verified uniform GO dispersion at low to moderate concentrations, with agglomeration observed at 1%, correlating with conductivity and stability trends. Mechanical testing indicated an initial reduction in stiffness and hardness at low GO loadings, followed by reinforcement at higher concentrations. Water uptake (WU) peaked at 0.125% GO before declining, while swelling ratio (SR) followed an inverse trend, optimizing dimensional stability and water management at 0.125% loading. Post-electrolysis, higher GO concentrations effectively limited swelling, confirming improved operational dimensional stability.
In conclusion, this study demonstrates that integrating GO into poly(co-aryl piperidinium) AEMs effectively enhances ion conductivity and mechanical stability, essential for advancing AEMWE at scale. The 0.125% GO concentration achieved highest water uptake (17%, up from 7% in the pristine membrane) and minimized swelling (6%, down from 13%), while the 0.5% loading delivered peak hydroxide conductivity (59 mS/cm, nearly doubling from 33 mS/cm) and improved operational mechanical stability (post-electrolysis swelling ratio of 27%, down from 37%), establishing this composition as a promising candidate for efficient AEMWE applications.