Layered Double Hydroxides (LDHs): Versatile and Powerful Hosts for Different Applications

Layered double hydroxides are an emerging and intriguing class of materials having unique structural properties that allow their application in very different fields, such as catalysis, pollution control, agriculture, electronic, nanomedicine and drugs delivery. They are constituted by a sheets structure with formula [M2+1-x M3+x (OH)2](An-)x/n yH2O (M2+= Zn, Mg, Fe, Ni, Co..; M3+=Al, Ga, Fe…; An- = nitrates, carbonates, chloride). The exchange of these counterions with others inorganic/organic species, producing hybrid nanocomposites, makes these systems ideal candidates for many application. The goal is to find the right cationic ratio and the proper experimental conditions (pH, temperature, time, concentrations) to make the exchange process rapid and with high yield. A large number of synthetic processes for the nanocomposites production are theoretically disposable: coprecipitation, ionic exchange, reconstruction, hydrothermal or sol-gel synthesis. We will briefly describe the structural features of LDHs and the most widespread synthetic procedures.