Natural double layered hydroxides: Structure, chemistry, and information storage capacity

Abstract

Layered double hydroxides (LDHs) constitute an important group of materials with many applications ranging from catalysis and absorption to carriers for drug delivery, DNA intercalation and carbon dioxide sequestration (Rives 2001; Duan and Evans 2006). The structures of LDHs are based upon double brucite-like hydroxide layers [Mn2+ Mm3+ (OH)2(m+n)]m+, where M2+ = Mg2+, Fe2+, Mn2+, Zn2+, etc.; M3+ = Al3+, Fe3+, Cr3+, Mn3+, etc. The positive charge of the layer is compensated by interlayer species that may consist of anions (CO32-, Cl-, SO42-, etc.) or both anions and cations (Na+, Ca2+, Sr2+, etc.).