Abstract: The electrolysis of water for hydrogen production facilitates the generation of green hydrogen devoid of carbon emissions, fulfilling the requirements of global energy advancement. Nonetheless, the anion exchange membranes (AEMs) presently employed in water electrolysis face the challenge of achieving an optimal balance between high conductivity and robust stability. By modifying covalent organic frameworks (COFs), the nanostructured "ion channel" framework QAxSLCOF-TpBpy can be engineered to transport ions effectively, exhibiting favorable ion selectivity alongside minimal water uptake and swelling ratio. Through meticulous control over ion channel density and the refinement of internal pore structures, it has been established that the grafting efficacy of short carbon chains is inferior to that of fluorinated groups. The composite membrane QAF3SLCOF-TpBpy@PPO demonstrates enhanced mechanical stability (27.32 MPa) compared to the unaltered membrane. Furthermore, the inherent hydrophobicity of fluorine functional groups allows for tunable adjustments within the membrane. Concurrently, the electrochemical properties of the membrane can be optimized, effectively addressing the trade-off dilemma associated with AEMs. Relative to the equivalent QAmSLCOF-TpBpy@PPO, the new membranes maintain a lower water uptake and swelling rate of 9.73 % and 6.98 %, respectively. These membranes are applied in water electrolysis for hydrogen generation. The composite anion exchange membrane (QAF3SLCOF-TpBpy@PPO) modified with QAF3SLCOF-TpBpy exhibited remarkable electrochemical performance in a custom-made MEA water electrolyzer, achieving a current density of 790.15 mA cm^-2 at a cell voltage of 2 V. These findings indicate that the modified AEMs hold significant promise for application in hydrogen production via water electrolysis.

Key words: Composite anion exchange membrane, Multi-structure ion channels, Ion channels concentration, Multiion transport simulation, Water electrolysis