Bio-Inspired 2D Asymmetric Nanochannels for High-Resolution Li

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+/Mg2⁺ separation for lithium extraction applications. During the forward transport of ions, the nGO nanochannels modified by sulfonate groups (SO3 -) with precise size provide hopping recognition sites and additional electrostatic attraction for the fast transport of Li+, while imposed Mg2+ dehydration and exposure to a stronger positive charge. The continuous pGO nanochannels modified by amino groups (NH3 +) further prevent the passage of dehydrated Mg2+ by enhanced electrostatic repulsion while allowing Li+ to transfer. Under the synergy of the two nanochannels, the JGOM demonstrates robust Li+/Mg2+ 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.