Functionalized MXene-reinforced PPO-based nanocomposite anion exchange membranes for high-performance water electrolysis

One of the major challenges in advancing anion exchange membrane water electrolysis (AEMWE) lies in addressing the trade-off between dimensional stability, electrochemical performance, and mechanical integrity of anion exchange membranes (AEMs). Overcoming these trade-offs is crucial for improving the performance and reliability of AEMWE systems. In this study, we tackled this challenge by developing a series of composite AEMs by reinforcing quaternized poly(phenylene oxide) (QPPO) with ammonium-functionalized MXene (NH4+-Ti3C2Tx) using a semi-interpenetrating (SNIP) polymer network technique. The resulting membranes exhibited significantly enhanced dimensional stability, electrochemical performance, mechanical strength, and thermal stability compared to the pristine QPPO membrane. Among the composite AEMs, QPPO-NH4-Mx-3.0 demonstrated the notable overall performance, achieving an impressive hydroxide (OH-) ion conductivity (IC) of 153.2 mS cm-1 at 80 °C-2.5 times higher than that of virgin QPPO. Additionally, the membrane displayed excellent tensile strength of 61.2 MPa, 4 times greater than that of the pristine QPPO, and achieved a peak current density of 2.1 A cm-2 at 2 V in 1 M KOH at 60 °C. The membrane also showcased exceptional alkaline stability, retaining 80.2% of its initial IC after three weeks of immersion in 1 M KOH. Durability testing further validated its robustness, with a stable operation maintained up to 150 h of electrolysis with a minimal voltage decay rate of 1.5 mV h-1. In summary, the QPPO-NH4-Mx-3.0 membrane demonstrates substantial promise as a high-performance AEM for advancing AEMWE technology, paving the way for more efficient and reliable water electrolysis systems.