Heterogeneity-Guided Interlayer Tuning in Vermiculite-MOF Membranes for Efficient Li⁺/Mg²⁺ Separation

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Engineering

Background:

• Separating lithium (Li+) and magnesium (Mg2+) ions is challenging for 2D membranes due to complex transport channels.
• Existing membranes struggle with precise ion separation because of tortuous and unregulated interlayer pathways.

Purpose of the Study:

• To develop a novel strategy for precise Li+/Mg2+ separation using engineered 2D membranes.
• To reprogram ion transport pathways in vermiculite membranes by incorporating metal-organic framework nanosheets.

Main Methods:

• Incorporation of ultrathin zirconium benzene-1,3,5-tricarboxylate (ZrBTB) metal-organic framework nanosheets into vermiculite (Vm) membranes.
• Utilizing heterogeneity-guided interlayer engineering to modify lamellar ion transport pathways.
• Systematic structural analysis to understand the effects of ZrBTB incorporation on nanochannels.

Main Results:

• The resulting vermiculite/ZrBTB heterolamina membranes showed reorganized interlayer nanochannels with enhanced Li+ transport.
• ZrBTB incorporation created sub-nanoconfinement domains and modified channel-wall charge, improving Li+/Mg2+ selectivity.
• The optimized membrane achieved a Li+ permeation rate of 0.379 mol m-2 h-1 and a Li+/Mg2+ selectivity of ~46.2.

Conclusions:

• Interlayer heterogeneity is a powerful design parameter for creating efficient 2D ion-sieving membranes.
• The developed strategy offers a generalizable approach for constructing next-generation membranes for selective ion separation under mild conditions.
• Rational selection of 2D metal-organic framework building blocks allows effective tuning of channel properties for ion separation.