Nanocomposite quaternized nanocellulose/polysulfone-based anion exchange membranes containing ion channels for water electrolysis

To address the “trade-off” challenge between ionic conductivity and stability in anion exchange membranes (AEMs), nanocomposite AEMs made from quaternized nanocellulose (QNC)/polysulfone (QPSF) have been fabricated and characterized extensively. These membranes were then employed in the electrolysis of water for hydrogen production, resulting in remarkable ionic conductivity and robust stability simultaneously. The ultrathin QNC/QPSF membrane exhibited a nanocomposite structure, where QPSF served as the polymer matrix, and QNC established three-dimensional networks integrated within the QPSF matrix. The ionic conductivity of the QNC/QPSF-70 % membrane remained at 46.95 mS/cm at 80 °C, showing an increase of 60 % compared to that of pristine QPSF membrane and 2.5-times higher than that of the commercial AEM (AMI-7001S), respectively. Meanwhile, the three-dimensional networks of nanocellulose enhanced the alkaline and dimensional stability (swelling ratio = 9.97 %, 70 °C) as well as the resistance to hydrogen crossover of the QNC/QPSF membrane for water electrolysis applications. Moreover, molecular dynamics (MD) simulations suggested better ionic transport characteristics and alkaline stability promoted by the ion channels present in the nanocomposite AEM. This was further confirmed by the AEMWE performance where the QNC/QPSF-70% membrane containing ion channels exhibited 4.7-times higher current density than that of the pristine QPSF membrane without QNC component.