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

Abstract

One of the major challenges in advancing anion exchange membrane water electrolysis (AEMWE) lies in addressing the trade-offs 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 addressed this challenge by developing a series of nanocomposite AEMs by reinforcing quaternized poly(phenylene oxide) (QPPO) with ammonium-functionalized MXene (NH4+-Ti3C2Tx). The resulting membranes exhibited significant enhancement in 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 contributed 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, achieved 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 demonstrates substantial promise as a high-performance AEM for advancing AEMWE technology, paving the way for more efficient and reliable water electrolysis systems.