THEORETICAL INVESTIGATION ON THE INFLUENCE OF INCORPORATEDNiIITO DISTORTION AND STABILITY OFCuII–AlLAYERED DOUBLE HYDROXIDES

Abstract

Based on the density functional theory, the structural information and energetic property of Ni–Cu–Al ternary layered double hydroxides were investigated by periodic lattice calculation as a function of cationic substitution. The results revealed that the incorporated NiIIcould improve the structural stability and crystalline perfection of the material. When the content of Ni increased, the charge of the metal cations would transfer to the hydroxyl groups, and the electronic configuration of CuIIand NiIIwould both change from their ideal states. Therefore, as CuIIcations were progressively replaced by NiII, the distortion of Cu(OH)6and Ni(OH)6octahedra would be weakened by enlarging the four short M–O bonds and shortening the two long ones. What is more, the distorted O–M–O bond angle changed to adapt the variety of M–O bond lengths. As a result, all the M(OH)6octahedra could share their edges more conveniently to format the LDHs structure. At last, we conclude that the averaged length of M–O bond and the electron configuration of the metal cations play a significant role in the synthesis of LDHs materials.