Layered Double Hydroxides: Tailoring Interlamellar Nanospace for a Vast Field of Applications

Abstract

Fifty-eight years ago Fenman, during an American Physical Society meeting at the California Institute of Technology, anticipated the problem of modifying and governing the world of the infinitely small. what is possible in principle… We are not doing it simply because we haven't yet gotten around to it." Useless to say how profound his sensibility for science was. We've just begun to walk in this enormous field, toward the assembly of devices atom by atom. What we did till now is still rudimentary. Anyhow we believe that Layered Double Hydroxides could play a role in manufacturing these nanometric equipments.Layered Double Hydroxides (LDHs) are 2D ionic lamellar nano-materials belonging to the group of anionic clays. Their structure consists of positively charged brucite-like layers and intercalated anions. The layered structure, together with the flexibility to intercept different anionic species in variable compositions, both inorganic and organic, has attracted increasing interest. In order to meet specific requirements in very distant fields, considerable efforts were made to tailor the physical/chemical properties of LDHs and to design engineered LDH for several applications, ranging from anticorrosion coatings, flame-retardants, catalysis, to water treatment/purification, and biomedical applications. Furthermore they have been applied in energy harvesting and conversion, thanks to the possibility of substituting the composing metals with transition metals.Within the framework of this contribution, we first briefly review the development of synthesis processes ( §1). In Paragraph 2, examples of the LDHs applications are reported. We will than focus on our laboratory experimental activities, showing the growth of the structures either on printed circuit tracks for applications of LDHs as gas sensors and biosensors. One more application is in nanostructured-modified textiles.

Curcumin Incorporation into Zn3Al Layered Double Hydroxides—Preparation, Characterization and Curcumin Release

“…Structurally, these solids consist of positively charged brucite-type layers with balancing anions and water molecules in the interlayer space [21]. Despite the fact that there is a scarce spreading of LDHs in the earth crust, several laboratory methods for their obtaining were developed: co-precipitation at a variable or constant pH, under low or high supersaturation conditions, sol-gel, hydrothermal and mechanochemical synthesis [21][22][23][24]. An interesting feature of the LDHs is the so-called "memory effect" which allows the reconstruction of the layered structure when the mixed oxide obtained by thermal decomposition of an LDH precursor at temperatures lower than 550 • C is immersed in an aqueous solution containing the desired compensation anion which can be either inorganic or organic [21,22].…”