Soft-chemical treatment of transition-metal-containing layered double hydroxides and their application in porous materials

Abstract

Layered double hydroxides (LDH) containing Co or Ni as the divalent cation and Al or Fe as the trivalent cation were prepared by hydrothermal treatment. The LDH phase containing Al can be prepared at a pH of ca. 7, whereas the LDH phase containing Fe can be prepared at pH 10. The chemical composition of the LDH was estimated by the calculation of the weighted mean electronegativity of the cations present in the aqueous metal solution. The decarbonated LDHs are intercalated by sodium dodecyl sulfate and can be exfoliated in 1-butanol solution by ultrasonication. The resulting LDH aggregates with a card-house structure that can then be deposited from these exfoliated colloidal solutions by sodium carbonate. For Ni/Al and Ni/Fe LDHs, in particular, the specific surface area and pore volume drastically increased owing to the card-house texture formed by exfoliation and redeposition.