Layered Double Hydroxides(LDHs) : Synthesis & Applications

Layered double hydroxides, a class of anionic clays possessing sandwich like structure in which negative anions are sandwiched into positively charged metal layers in a repeating manner, have been studied extensively. Layered double hydroxides could be fabricated with combination of different divalent (Cd2+, Mn2+, Fe2+, Pb2+) and trivalent (Al3+, Cr3+, Fe3+) metals and layered arrangement imparts unique properties such as adsorption properties and catalytic properties in these compounds. Exciting feature of these compounds is the memory effect. There are a number of methods to synthesize these layered compounds, such as co-precipitation, hydrothermal, sol-gel, urea hydrolysis, etc. The synthesized LDHs can be characterized morphologically and compositionally i.e. scanning electron microscopy, transmission electron microscopy, powder X-Ray diffraction, Mossbauer spectroscopy, thermogravimetric analysis, XPS, etc. The wonderful feature of layered double hydroxides is the pliancy of interlayer space enabling them to accommodate various anionic species, and high surface area making them efficient in numerous applications such as adsorbents, anion exchange, catalysts, and biological compatible.