Tailoring Sub‐Nanochannels and Ion‐Imprinted Functionality of Palygorskite‐Derived Membranes for Desalination and Lithium‐ion Transport

Nanofiltration membranes with tailorable sub‐1‐nm channels are essential for desalination and ion separation, yet scalable and eco‐friendly fabrication of function‐switchable membranes remains a formidable challenge. Here, we report a Palygorskite‐carboxymethylcellulose hybrid membrane platform that achieves dual functionality through precise channel engineering. Coordination‐driven self‐assembly in water yields two distinct membrane types from the same material system. The desalination membrane preserves the intrinsic sub‐1‐nm channels of Palygorskite nanorods, delivering high water permeance (>23 L m −2 h −1 bar −1 ) and a Na 2 SO 4 rejection (>99%). By contrast, the Li + /Mg 2+ separation membrane is constructed from acid‐etched nanorods bearing Mg 2+ ‐imprinted sites, affording expanded channels that enable selective Li + transport while capturing Mg 2+ via imprinting adsorption. This membrane achieves a Li + /Mg 2+ selectivity of approximately 175 in mixed solutions. Molecular dynamics simulations indicate rapid and selective transport of water and Li + through the respective sub‐1‐nm channels. Beyond superior separation performance, the membranes exhibit robust mechanical strength, long‐term operational stability, and excellent antifouling and antimicrobial properties. This one‐platform, dual‐function strategy demonstrates the scalable fabrication and tunable performance essential for practical water purification and lithium resource recovery.