Heterostructure‐Engineered Conductive MOFs Coupled with MoSe ₂ @MXene Framework for Efficient and Selective Lithium Extraction from Salt Lake Brine via Capacitive Deionization

Sustainable recovery of lithium from salt lake brines is essential for the transition toward clean energy but remains challenged by low Li⁺ concentrations and high Mg²⁺ interference. Herein, we develop a heterostructure-engineered ternary composite, conductive metal-organic frameworks (c-MOFs) coupled with a MoSe₂@MXene framework for efficient and selective lithium extraction by capacitive deionization (CDI) technology. The c-MOFs Fe- tetrahydroxybenzoquinone (Fe-THBQ) provide abundant redox-active sites for Li⁺ capture, while the MoSe₂@MXene framework accelerates ion transport rate and provides structural robustness. X-ray absorption spectroscopy (XAS) confirms that strong interfacial Fe─Se coordination bonds establish a continuous Fe-Se-Mo charge-transfer pathway for enhanced conductivity and ion selectivity. Thus, the Fe-THBQ@MoSe₂@MXene electrode delivers exceptional Li⁺ capture capacity (4.05 mmol g^-1), ultrafast adsorption rate (0.98 mmol g^-1 min^-1), superior cycling stability (91.3% retention after 50 cycles), and remarkable Li⁺ selectivity with high Mg/Li ratios in both model solutions and real Dachaidan salt lake brine. Ex situ X-ray diffraction analyses reveal a dual Li⁺ storage mechanism involving Fe²⁺/Fe³⁺ redox activity and reversible interlayer intercalation. Importantly, density functional theory (DFT) calculations confirm a substantially lower migration barrier for Li⁺ (0.052 eV) compared to competing cations, underpinning the observed selectivity. This work highlights a rational heterostructure design strategy for advancing CDI technology in lithium recovery.