Recently, the research team led by Professor Qiao Jinli from College of Environmental Science and Engineering in DongHua University has made significant progress in the field of alkaline water electrolysis for hydrogen production. The related findings, titled "Synergistic optimization of pore structure and hydrophilicity for an ultrathin, high-safety composite diaphragm toward high-current, durable alkaline water electrolysis," have been published in Science Bulletin
(Original link to this article: https://doi.org/10.1016/j.scib.2026.05.070).
To address the trade-off among thickness, ionic conductivity, and gas impermeability in composite diaphragms which serve as a core component of alkaline water electrolysis (AWE), the team proposed a facile, cost-effective, and easily scalable strategy that simultaneously regulates the pore structure of the composite diaphragm and renders it hydrophilic. This enabled the successful fabrication of an ultrathin composite diaphragm with a thickness of only 220 mm, whose performance far exceeds that of the commercial third-generation composite diaphragm represented by Belgium's Afga. By introducing sodium carboxymethyl cellulose (CMC), the team constructed a three-dimensional supramolecular hydrogen-bonding network of CMC, PVP, and ZrO₂ within the diaphragm, achieving excellent stability of the ultrathin composite diaphragm under harsh operating conditions. More critically, a continuous nanoporous structure with low tortuosity was formed. This unique nanoporous channel structure not only provides high-speed transport channels for OH⁻ but also maintains outstanding gas barrier performance. Moreover, the hydroxyl and carboxyl functional groups abundant in CMC effectively reduce the wetting resistance of the electrolyte to the diaphragm, further accelerating OH⁻ conduction.
Figure 1. (a) Schematic illustration of the preparation process of the CMC–ZrO₂/PSU series diaphragms. Photographs of the CMC2Z83 diaphragm: (b) surface, (c) rolled state, and (d) large-area diaphragm (52 × 54 cm²)
Figure 2. Basic property characterization of the CMC–ZrO₂/PSU series diaphragms. (a) Incremental intrusion curves of Zirfon UTP 220 and the CMC–ZrO₂/PSU series diaphragms measured by mercury porosimetry, as a function of pore diameter; (b) porosity, (c) bubble point pressure, (d) contact angle, (e) electrolyte uptake in 30 wt% KOH, and (f) area resistance of the CMC–ZrO₂/PSU series diaphragms; (g) OH⁻ transport mechanism of the CMC–ZrO₂/PSU series diaphragms
Figure 3. AWE performance of the CMC–ZrO₂/PSU series diaphragms. (a) Schematic illustration of the home-made alkaline water electrolyzer. Polarization curves of Zirfon UTP 220, CMC0Z85, and CMC2Z83 diaphragms measured in (b) 30 wt% KOH and (e) 10 wt% KOH; EIS plots of Zirfon UTP 220, CMC0Z85, and CMC2Z83 diaphragms measured in (c) 30 wt% KOH and (f) 10 wt% KOH; (d) area resistance of Zirfon UTP 220 and CMC2Z83 diaphragms as a function of KOH concentration; (g) comparison of the current density of CMC2Z83, CMC5Z80, and CMC8Z77 diaphragms with previously reported AWE diaphragms at a cell voltage of 1.8 V
Figure 4. Molecular dynamics simulations of water transport in the CMC–ZrO₂/PSU diaphragm. (a) Schematic structural model of the diaphragm assembly; (b) structural model of ZPCH; (c) water diffusion curves of the ZPH and ZPCH models
In this study, a single-electrolyzer system equipped with the CMC2Z83 diaphragm achieved an ultrahigh current density of 2.2 A/cm² at a cell voltage of 2.0 V, along with the production of high-purity gases (at a current density of 0.2 A/cm², the AHCs were only 0.09%). Meanwhile, a short stack equipped with the CMC2Z83 diaphragm operated continuously for 30 days (~720 h) under dynamic conditions (start-stop, high-low temperature, and high-low current density switching) without degradation or powder detachment, maintaining highly stable structural and electrochemical performance.
In addition, in recent years, Professor Qiao Jinli's team, with the support of the National Natural Science Foundation of China, the National Key Special Project for International Cooperation of the Ministry of Science and Technology, and the Key Basic Research Program of the "Science and Technology Innovation Action Plan" of the Shanghai Municipal Science and Technology Commission, has achieved a series of results in the development of high-performance composite anion exchange membranes and their application to hydrogen production by water electrolysis and rechargeable zinc-air batteries, which have been successively published in Adv. Funct. Mater., 2026; Energy Mater. Adv., 2026; J. Mem. Sci. 2025, 735, 124583; Chem. Eng. J., 2025, 510, 161697; Adv. Funct. Mater., 2024, 2410009; and eScience, 2024, 4, 100290.
