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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. [ABSTRACT FROM AUTHOR]

Oil spill leakage and industrial oily wastewater discharge into water bodies cause a considerable threat to the marine network and human health. Selective oil/organic solvent collection devices with effectual recovery of the oils from the water surface have been studied through engineering advanced materials displaying a special wetting property. Herein, we develop a water-repellent MIL-101-(Fe) material supported over fluorinated graphene (FG) nanosheets by in situ synthesis under ambient conditions. FG nanosheets not only provide the necessary structural nodes for the growth of octahedral MIL-101-(Fe) nanostructures but also bring in the necessary hydrophobicity with a water contact angle of 146 ± 1°, possessing a surface free energy of 12.7 mJ m–2. Powdered FG-MIL-101-(Fe) demonstrated differential wettability with extreme chemical stabilities toward acidic and basic water. The solution processability of FG-MIL-101-(Fe) was amalgamated with a copper mesh and a polydimethylsiloxane sponge via spray coating and inoculation methods en route designing oil recovery prototypes. The submersible FG-MIL-101-(Fe)-PDMS sponges displayed selective pickup of oil and organic solvents with the sorption ranging from 1.85 to 3.8 g/g, in addition to displaying recyclability up to 10 cycles along with physical and chemical robustness. Additionally, the FG-MIL-101-(Fe)-PDMS macroporous sponge was subjected to demulsification of a toluene/water system taking the distinct toluene pickup property. Selective oil recovery containers were fabricated by directing FG-MIL-101-(Fe) suspensions on a copper mesh resulting in oil-collecting devices. Organics/oils selectively infiltrated into the FG-MIL-101-(Fe)-coated copper mesh superwetting containers with separation efficiencies in the range of 96–100%. The translation of FG-MIL-101-(Fe)-modified substrates was utilized to tackle real-time oil/organic collection prototypes from oil–seawater mixtures under turbulent conditions demonstrating excellent sorption abilities ranging from 4.4 to 5.6 g/g (by superwetting sponges) along with super efficiencies in the range of 92–98% (via superwetting containers). [ABSTRACT FROM AUTHOR]

Although artificial capsule structures have been thoroughly investigated, functionality at the surfaces of their interiors has been surprisingly overlooked. In order to exploit this aspect of capsular structure, we here report the breakthrough fabrication of metallic (platinum) microcapsules with sufficient accessibility and electroactivity at both interior and exterior surfaces (open- mouthed platinum microcapsules), and also we demonstrate improvements in electrochemical and catalytic functions to emphasize the practical importance of our concept. The open- mouthed platinum microcapsules were prepared by template synthesis using polystyrene spheres, where surface-fused crystalline nanoparticles formed a capsule shell. Subsequent removal of the polystyrene spheres induced formation of mouth-like openings. The open-mouthed platinum microcapsules exhibit a substantial increase of their electrode capability for methanol oxidation and catalytic activities for carbon monoxide (CO) oxidation. Notably, activity loss during CO oxidation due to undesirable particle agglomeration can be drastically suppressed using the open-mouthed microcapsules. [ABSTRACT FROM AUTHOR]

A novel Pt nanoparticle (Pt NP) embedded aminoclay/Nafion (Pt/AC/N) nanocomposite catalyst film was prepared for oxygen reduction reaction by sol-gel method. The prepared nanocomposite films were surface characterized using XRD and TEM and thermal stability was studied by TGA. The prepared film has firmly bound Pt NP and could exhibit an improved electro-reduction activity compared to vulcan carbon/Nafion supported Pt NP (Pt/VC/N). Moreover, the Pt/AC/N film possessed good stability in the acidic environment. The limiting current density of the Pt/AC/N film with 35.4 μg/cm(2) of Pt loading was found to be 4.2 mA/cm(2), which is 30% higher than that of the Pt/VC/N. The maximum H2O2 intermediate formation was found to be ∼1.6% and the reaction found to follow a four electron transfer mechanism. Accelerated durability test for 2000 potential cycles showed that ca. 78% of initial limiting current was retained. The results are encouraging for possible use of the Pt/AC/N as the free-standing electrocatalyst layer for polymer electrolyte membrane fuel cells.

Water-dispersible aminoclay synthesized in a single step process was used as an inorganic filler for preparing polyvinyl alcohol (PVA)-clay hybrid films. The PVA-clay hybrid films with different weight percentages of aminoclay were obtained by simple mixing and casting of aqueous solutions of clay and polymer. The composite films show excellent retention of ductile behavior of the polymer, PVA, even at higher loadings (20 wt %) of aminoclay. Introduction of aminoclay stabilized Ag nanoparticles significantly improved the mechanical properties of the composite film. The oxygen barrier property of the composite film was improved with the increase in composition of the clay.