Nano/Microporous Materials: Nanostructured Layered Double Hydroxides

Abstract

AbstractThis review summarizes developments in nanostructured layered double hydroxide (LDH) materials for the period 2004–2007. Particular attention is paid to synthesis aspects, including coprecipitation, urea decomposition, sol‐gel processing and derivative methods as well as the generation of functional materials through delamination either from solvent solution or in situ within a polymer. Coating processes, illustrated by the heterogeneous growth of nanorods onto LDH surfaces, is distinguished from particle nanostructuration. In addition, nanostructuration from LDH frameworks is described for iron‐based oxides and other metal oxides in which catalytic, magnetic, or energy‐storage properties are discussed. Other examples of nanostructuration, such as complex encapsulation, are demonstrated not only with different complexes, such as polyoxometallates and porphyrines but also with rare earth and quantum dot materials, where interest is focused on luminescent and optical properties. Additionally, drug encapsulation and/or release, gene‐reservoir applications, and incorporation of DNA and bioinorganic enzymes into LDH assemblies nicely illustrate biologically related uses of LDH nanoplatelets. Finally, reactions occurring within LDH interlayer spaces are described, and the role of LDH framework as a nanoreactor is illustrated by in situ polymerization of conjugated polymers and thermoplastics. LDH materials can also be used as sacrificial templates for fabricating nanosized polymers and for the synthesis of carbon replica and carbon fibers.