Edge‐Functionalized Graphene Nanoribbons/Graphene Nanofiltration Membrane for Solar‐Driven Lithium Recovery From Brine

ABSTRACT Selective lithium extraction from high‐concentration brines remains challenging due to high Mg 2 + ion concentration and strong hydration energy contrast between Mg 2 + and Li + . Here, we introduce a solar‐driven nanofiltration platform that integrates edge‐functionalized graphene nanoribbons (GNRs) with photothermally reduced graphene oxide (PrGO) to establish sub‐nanometer ion coordination channels for efficient Li + ion separation. The GNRs provide densely distributed functional groups that promote Li + dehydration and rapid hopping between coordination sites, while PrGO reinforces structural stability. Density functional theory (DFT) calculations reveal strong interfacial coupling (ΔE int = −3.45 eV), substantial charge redistribution, and markedly lower Li + migration barrier (0.18–0.31 eV) compared to other ions. The optimized GNRs/PrGO 15 NF membrane achieves a Li + permeation rate of 0.253 mol m − 2 h − 1 and Li + /Mg 2 + selectivity of 21 in static permeation tests. Solar‐driven operation coupled with a photothermal substrate, significantly enhance the ion descrimination. Under 2‐sun irradiation, the system achieves a separation factor of 26 and reduces the Mg 2 + / Li + ratio from 19.8 to 0.7, resulting in a 28‐fold Li + enrichment. The synergetic GNRs/PrGO frameworks offer a scalable, sustainable route for efficient solar‐driven Li + extraction from brines.