Interface hyperfine coupling engineering of graphene oxide@MgAl-LDH architectures toward eco-efficient lithium...

Layered double hydroxides (LDHs) hold promise for lithium (Li) extraction from salt-lake brines, owing to their distinctive layered structure and ion-exchange capability. However, the challenge of precisely modulating their electronic structure limits adsorption selectivity and capacity toward lithium-ion (Li⁺). Herein, MgAl-LDH nanosheets are anchored on graphene oxide (GO) (GO@MgAl-LDH) via an in-situ growth method to achieve efficient Li⁺ extraction. The experimental and theoretical calculations pinpoint that the hyperfine coupling interaction between GO and MgAl-LDH modulates the electronic structure of interlayer CO₃^2- in MgAl-LDH, thereby optimizing the active sites for Li⁺ adsorption. This hyperfine coupling interaction endows the optimized GO@MgAl-LDH composite with a maximum adsorption capacity of 12.96 ± 0.50 mg·g^-1 in simulated salt-lake brine, which is 3.00 and 4.56 times higher than those of pure MgAl-LDH (4.31 ± 0.35 mg·g^-1) and GO (2.84 ± 0.46 mg·g^-1), respectively. Practical applications in 11 representative salt-lakes across the Qinghai-Tibet Plateau of China demonstrate that the GO@MgAl-LDH maintains remarkable Li⁺ adsorption performance in real brines, with a maximum adsorption capacity of 5.92 ± 0.18 mg·g^-1 in East Taigener Lake. Ecological assessments based on microbial diversity and water quality analyses exhibit that the GO@MgAl-LDH does not induce water quality deterioration, thus ensuring its environmental safety and compatibility.