Heterostructure-Engineered Conductive MOFs Coupled with MoSe₂@MXene Framework for Efficient and Selective Lithium...

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.