Influence of interlayer anion on supermolecular interaction in quaternary hydrotalcites

Abstract

A periodic interaction model with different intercalated anions (X=F-, Cl-, Br-, I-, NO-3, OH-) is proposed for the CuZnMgAl quaternary hydrotalcites (CuZnMgAl-X). Based on density functional theory, the CuZnMgAl-X geometry was optimized using the CASTEP program. The distribution of anions in the interlayer, and the supra-molecular interaction between host layer and guest anions were investigated by analyzing binding energies, geometric parameters, Mulliken populations, hydrogen-bonding and densities of states. A decreased electronegativity of interlayer anion caused a transfer of charge from guest anions to host layer and a gradual decrease in the strength of electrostatic interaction and hydrogen bonding. The system band gap narrowed, electrons transferred to higher energy levels more easily, and the overall stability of the system decreased. The Cu dopant caused a deviation in CuZnMgAl-X valence band to high energies. Compared with traditional layered double hydroxides, the band gap narrowed and stability decreased, accounting for the difficulty in preparing copper-containing hydrotalcites. © Editorial office of Acta Physico-Chimica Sinica.