Theoretical investigations on the layer-anion interaction in Mg-Al layered double hydroxides: influence of the anion nature and layer composition

Cristina Cuautli; Joel Ireta

doi:10.1063/1.4913570

Theoretical investigations on the layer-anion interaction in Mg-Al layered double hydroxides: influence of the anion nature and layer composition

J Chem Phys. 2015 Mar 7;142(9):094704. doi: 10.1063/1.4913570.

Authors

Cristina Cuautli¹, Joel Ireta¹

Affiliation

¹ Departamento de Química, División de Ciencias Básicas e Ingeniería, Universidad Autónoma Metropolitana-Iztapalapa, A. P. 55-534, México D.F. 09340, México.

PMID: 25747096
DOI: 10.1063/1.4913570

Abstract

The influence of the anion nature and layer composition on the anion-layer interaction in Mg-Al layered double hydroxides (LDHs) is investigated using density functional theory. Changes in the strength of the anion-layer interaction are assessed calculating the potential energy surface (PES) associated to the interlayer anion (OH(-)/Cl(-)) in Mg-Al-OH and Mg-Al-Cl LDHs. The layer composition is varied changing the divalent to trivalent cation proportion (R). Mg-Al-OH is thus investigated with R = 2, 3, 3.5 and Mg-Al-Cl with R = 3. It is found that the PES for OH(-) in Mg-Al-OH/R = 3 presents wider energy basins and lower energy barriers than any other of the investigated compositions. It is shown that the latter is connected to the number of hydrogen bonds formed by the anions. These results have interesting implications for understanding the enhancement of the physicochemical properties of LDHs upon changing composition.