Synergistic Engineering of Membrane–Electrode Interfaces via Surface Patterning in Anion Exchange Membrane Water Electrolysis

ABSTRACT The membrane–electrode interface critically governs the performance and durability of anion exchange membrane (AEM) water electrolysis, yet engineering these interfaces in pre‐formed hydrocarbon AEMs remains challenging due to their high glass‐transition temperatures and thermally degradable quaternary‐ammonium cations. Here, we report a dual‐side patterning strategy enabled by localized solvent‐induced surface softening combined with plasma‐treated, gas‐permeable polydimethylsiloxane molds, allowing capillary‐driven pattern transfer without additional external pressure. Pillar (5 µm) and prism (10 and 20 µm pitch) features are uniformly replicated on both surfaces of a representative pre‐formed hydrocarbon AEM while preserving bulk membrane properties. Decoupled cathode‐, anode‐, and dual‐side patterning analysis reveals that both interfaces contribute, with the anode dominating and dual‐side patterning yielding a 12.6% synergistic enhancement (4.65 vs. 4.13 A cm −2 at 2.0 V, 1.0 M KOH); under electrolyte‐deficient conditions (1.0 mM KOH), this enhancement is amplified to 31%, supported by concentration‐dependent double‐layer capacitance analysis. The three‐dimensional interlocked architecture also strengthens interfacial adhesion and, under dynamic load cycling (200 cycles, 400 h), suppresses catalyst‐layer detachment relative to the flat reference. These findings establish dual‐side membrane patterning as a structural route to enhance both performance and interfacial robustness in AEM water electrolysis.