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Image: see text Interlayer spacing and structure stability of layered double hydroxides (LDHs) on their application performance in adsorption, ion exchange, catalysis, carrier, and energy storage is important. The effect of different interlayer anions on the interlayer spacing and structure stability of LDHs has been less studied, but it is of great significance. Therefore, based on density functional theory (DFT), the computational model with 10 kinds of anions intercalated Ni(3)Al-A-LDHs (A = Cl(–), Br(–), I(–), OH(–), NO(3)(–), CO(3)(2–), SO(4)(2–), HCOO(–), C(6)H(5)SO(3)(–), C(12)H(25)SO(3)(–)) and four Ni(R)Al-Cl-LDH models with different Ni(2+)/Al(3+) ratios (R = 2, 3, 5, 8) were constructed to calculate and analyze interlayer spacing, structural stability, and their influence factors. It was found that the interlayer spacing order of Ni(3)Al-A-LDHs intercalated with different anions is OH(–) SO(4)(2–) > OH(–) > Cl(–) > Br(–) > I(–) > HCOO(–) > NO(3)(–) > C(12)H(25)SO(3)(–) > C(6)H(5)SO(3)(–). The smaller the interlayer spacing, the higher the binding energy and the stronger the structural stability of LDHs. The factors affecting structural stability mainly include the bond length and bond angle of the hydrogen bond and the charge interaction between the basal layer and interlayer anion. In the CO(3)(2–) intercalated system, the hydrogen bond length exhibits the shortest of 1.95 Å and the largest bond angle of 163.68°. The density of states and energy band analysis show that the higher the number of charges carried by the anion, the stronger its ability to provide electrons to the basal layer.
Wang et al. (Fri,) studied this question.