Synthesis of uniform Ni-Al layered double hydroxide via a novel reduction-oxidation route

Ni-Al layered double hydroxides (LDHs) were successfully synthesized through a novel reduction-oxidation route, which involved a rapid reduction of Ni2+ cations and nucleation in a colloid mill, followed by an oxidation of metallic nickel nuclei and structural transformation under hydrothermal conditions in the presence of sodium carbonate. The results indicated that the concentration of sodium carbonate and hydrothermal reaction temperature had important influence on the growth of LDH phase, and NiAl-LDH crystals with high crystallinity and good homogeneity could be achieved under the optimal conditions. The possible formation mechanism of a NiAl-LDH compound was proposed tentatively. The present work provided a new method for a scale-up synthesis of a variety of well-crystallized LDH materials. (C) 2012 Elsevier B.V. All rights reserved.