Wang Wenguang, Zhang Yanqiu, Wang Chao, Sun Haixiang, Guo Jing, Shao Lu
State Key Laboratory of Urban Water Resource and Environment, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, 150001, Harbin, China.
School of Materials Science and Engineering, China University of Petroleum (East China), 266580, Qingdao, China.
Angew Chem Int Ed Engl. 2024 Sep 9;63(37):e202408963. doi: 10.1002/anie.202408963. Epub 2024 Aug 6.
Sub-nanoporous membranes with ion selective transport functions are important for energy utilization, environmental remediation, and fundamental bioinspired engineering. Although mono/multivalent ions can be separated by monovalent ion selective membranes (MISMs), the current theory fails to inspire rapid advances in MISMs. Here, we apply transition state theory (TST) by regulating the enthalpy barrier (ΔH) and entropy barrier (ΔS) for designing next-generation monovalent cation exchange membranes (MCEMs) with great improvement in ion selective separation. Using a molecule-absorbed porous material as an interlayer to construct a denser selective layer can achieve a greater absolute value of ΔS for Li and Mg transport, greater ΔH for Mg transport and lower ΔH for Li transport. This recorded performance with a Li/Mg perm-selectivity of 25.50 and a Li flux of 1.86 mol ⋅ m ⋅ h surpasses the contemporary "upper bound" plot for Li/Mg separations. Most importantly, our synthesized MCEM also demonstrates excellent operational stability during the selective electrodialysis (S-ED) processes for realizing scalability in practical applications.
具有离子选择性传输功能的亚纳米多孔膜对于能源利用、环境修复和基础生物启发工程至关重要。尽管单价/多价离子可以通过单价离子选择性膜（MISM）进行分离，但目前的理论未能推动MISM取得快速进展。在此，我们应用过渡态理论（TST），通过调节焓垒（ΔH）和熵垒（ΔS）来设计下一代单价阳离子交换膜（MCEM），以大幅提高离子选择性分离性能。使用分子吸附的多孔材料作为中间层来构建更致密的选择性层，可以实现Li和Mg传输的ΔS绝对值更大、Mg传输的ΔH更大以及Li传输的ΔH更低。这种记录的性能表现为Li/Mg渗透选择性为25.50，Li通量为1.86 mol⋅m⋅h，超过了当代Li/Mg分离的“上限”图。最重要的是，我们合成的MCEM在选择性电渗析（S-ED）过程中也表现出出色的操作稳定性，以实现实际应用中的可扩展性。
