Bio‐Inspired 2D Asymmetric Nanochannels for High‐Resolution Li <sup>+</sup> /Mg <sup>2+</sup> Separation
Shuai Wang, Chuanjie Fang, Yi Huang, Ruobing Yi, Mengjiao Wu, Yan Wang, Fupeng Li, Liping Zhu, Shanshan Liang, Liang Chen
Abstract
Abstract Extracting lithium from salt lake brines is crucial to achieve sustainable development of lithium resources. However, it remains a major challenge to design nanochannels with efficient selectivity and fast transport for target ions. Here, inspired by biological membranes, we reported a Janus graphene oxide membrane (JGOM) with an asymmetric structure that exhibits diode‐like ion transport behavior and achieves high‐efficiency Li + /Mg 2 ⁺ separation for lithium extraction applications. During the forward transport of ions, the nGO nanochannels modified by sulfonate groups (SO 3 − ) with precise size provide hopping recognition sites and additional electrostatic attraction for the fast transport of Li + , while imposed Mg 2+ dehydration and exposure to a stronger positive charge. The continuous pGO nanochannels modified by amino groups (NH 3 + ) further prevent the passage of dehydrated Mg 2+ by enhanced electrostatic repulsion while allowing Li + to transfer. Under the synergy of the two nanochannels, the JGOM demonstrates robust Li + /Mg 2+ separation performance, outperforming symmetrical structure GO membranes and other reported membranes, which was further confirmed by simulation results. This study provides a new insight into the rational design of ion sieving membranes.