Molecular stapling by in-situ NiFe-LDH growth in poly(terphenyl piperidinium) anion exchange membranes for durable electrolysers

The commercial viability of Anion Exchange Membrane Water Electrolysis (AEMWE) is currently impeded by a fundamental materials paradox: an inverse relationship between ionic conductivity and dimensional stability. A high ion-exchange capacity is required for efficient hydroxide transport but invariably induces excessive water uptake, leading to severe swelling and accelerated degradation. Here, we report a novel nanocomposite strategy to overcome this trade-off through the in situ growth of nickel‑iron Layered Double Hydroxide (NiFe-LDH) nanoplatelets within a rigid poly(terphenyl piperidinium) (PTP) matrix. Structural analysis confirms that these inorganic platelets act as “molecular staples,” establishing an extensive hydrogen-bonding network that physically crosslinks the polymer chains. This architecture effectively decouples water uptake from macroscopic deformation: the composite membrane suppresses in-plane swelling by 55% (from 25.3% to 11.4% at 80 °C) while simultaneously serving as hydrophilic reservoir that boosts hydroxide conductivity to 145 mS cm −1 . Furthermore, accelerated aging tests (1800 h in 6 M KOH at 80 °C) revealed exceptional alkaline stability, significantly outperforming the pristine membrane (79%). The composite membrane was subsequently assessed in a full water electrolysis cell, where it exhibited high performance, achieving current densities of 2.7 A cm −2 (120 μm membrane thickness) and 5.3 A cm −2 (50 μm) at 2.2 V and 80 °C, along with prolonged durability exceeding 300 h under dynamic operating conditions. Collectively, these results highlight in situ molecular stapling as a powerful design strategy for next-generation ionomers, enabling the robust performance required for industrial-scale hydrogen production.