Applications of Lamellar Membranes Reconstructed from Clay Mineral-Based Nanosheets: A Review

Owing to their abundance, ecofriendliness, and multifaceted properties, natural clay minerals are among the most trusted and widely utilized materials on earth. One of the most exciting and latest findings of these minerals is that their layers can be exfoliated into individual flakes and reassembled to produce freestanding and flexible membranes. A tremendous surge in the research related to the futuristic applications of lamellar membranes prepared by restacking exfoliated two-dimensional (2D) nanomaterials has been observed in recent years. In this review article, we aim to summarize the multidirectional progress of lamellar membranes prepared from natural clay minerals. Innovative strategies involved in the exfoliation of clay layers and fabrication of macroscopic membranes through various assembly techniques are highlighted with special emphasis on novel applications such as studying nanofluidic transport in strict 2D, fabrication of smart materials, carrying out chemical reactions under nanoscale confinement, harvesting blue energy, and molecular separation. The clay membranes also inherit extraordinary robustness from their parent minerals and hence open up novel avenues for unique combinations of delicate properties and extraordinary thermal and chemical stability such as high-temperature stable ionic conductors, thermally stable smart materials, and high-temperature energy devices. Exceptional properties imbued to natural clay minerals such as tunable surface wettability and water-assisted healing of physical damage and functional properties by exchanging their inherent interlayer cations are also discussed elaborately.