Synergistic Engineering of Ethyl Cellulose and Etched ZrO2 Nanoparticles for Tailored Microporous Composite Membranes Toward Efficient Alkaline Water Electrolysis

Alkaline water electrolysis (AWE) is a mature and green technology for producing hydrogen, yet existing separators generally suffer from low ionic conductivity and insufficient mechanical stability. In this work, a synergistic design strategy is proposed by coupling a polysulfone (PSU)/ethyl cellulose (EC) blended organic framework with hydrofluoric acid etched zirconia (Et‐ZrO 2 ) nanoparticles. A differentiated microporous, ion‐conductive composite membrane is fabricated via a non‐solvent‐induced phase separation (NIPS) process, yielding a hierarchical channel structure combining finger‐like and sponge‐like pores. Hydroxyl groups in EC form continuous hydrogen‐bonding networks within the membrane, introducing the Grotthuss conduction mechanism to accelerate OH − transport. The rough cracks on the surface of Et‐ZrO 2 establish micro‐mechanical interlocking with the polymer matrix, enhancing interfacial adhesion and channel hydrophilicity. The optimally formulated EC‐3 separator exhibits a low area resistance (0.14 Ω·cm 2 ), high bubble point pressure (4.52 bar), and stable electrolysis performance, achieving a current density of 1.32 A·cm −2 at 2 V in 30 wt.% KOH at 80 °C, with hydrogen purity reaching 99.98% at 1.2 A·cm −2 , and maintaining continuous operation for 1000 h at 1.0 A·cm −2 with the cell voltage consistently below 2.2 V. Molecular dynamics simulations confirm that EC markedly strengthens the interaction between OH − and the membrane matrix, facilitates hydroxide transfer, and increases the ionic diffusion coefficient. This study achieves a balance between gas‐barrier properties and high ionic conductivity, offering a new perspective for the design and industrial application of high‐performance AWE separators.