Hydrogen-bonded QSEBS/ZrO2 2 mixed matrix anion exchange membranes for water electrolyzer

We present an innovative approach to address the challenges associated with swelling and alkaline stability in anion exchange membranes (AEMs). Our strategy involves integrating hydrogen-bonded ZrO2 2 nanoparticles into quaternized polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene (QSEBS) block copolymer to create a mixed matrix membrane (MMM). To augment the free volume within the polymer matrix and introduce hydrogen bonding sites for interaction with ZrO2, 2 , we incorporated a long-alkyl side chain with a ketone group through Friedel-Crafts acylation. Incorporating ZrO2 2 nanoparticles creates additional ion-transporting water channels due to its high-water adsorption capacity, stemming from uncompensated bonds on its surface. This surface-bound water layer facilitates the rapid transport of solvated hydroxide ions while protecting vulnerable polymer chains from damage. We fabricated MMMs based on QSEBS with varying loads of ZrO2 2 nanoparticles (0 %, 3 %, 6 %, 10 % by weight), resulting in AEMs exhibiting gradual enhancements in ionic conductivity and alkaline stability with increasing ZrO2 2 content. The water electrolysis cell equipped with a QSEBS/ZrO2 2 6 wt% MMM demonstrates enhanced performance, achieving a current density of 1.19 A/cm2 2 at 2.0 V. This outperforms the neat QSEBS membrane, which achieves 0.86 A/cm2 2 at 2.0 V, and exhibits a substantial improvement of 80 % compared to the commercial FAA-3-50 membrane, which achieves 0.66 A/cm2 2 at 2.0 V.