镍镁铝类水滑石的超分子结构、电子性质及稳定性

以Ni²⁺同晶取代Mg²⁺的方式构建镍镁铝类水滑石(HT)的周期性计算模型, 通过进行密度泛函理论计算,研究了含镍水滑石的的超分子结构、电子性质及稳定性. 结果表明, 随着镍离子逐渐取代镁离子, 金属离子之间的平均距离逐渐减小, 层间距逐渐增大, 与实验结果一致. 与此同时, 电子逐渐从主体层板向客体阴离子传递,导致主客体之间的静电作用力及整体超分子作用力逐渐增强, 结合能的绝对值逐渐增大, 体系的稳定性增加.在微观结构上, 电子传递行为使层板中平均金属―氧键键长逐渐减小, 且金属配位角的畸变情况得到一定程度的缓解, 这些变化都有利于形成更稳定的体系, 说明镍铝类水滑石在理论上比镁铝水滑石更稳定.

Supramolecular Structure,Electronic Property and Stability of Ni-Mg-Al Layered Double Hydroxides

We established periodical structures for Ni-Mg-Al hydrotalcites (HT) by isomorphous substitution of Mg²⁺ with Ni²⁺. We discussed the supramolecular structure, electronic property, and stability of the systems according to computational results based on density functional theory. As Ni²⁺ content of increased, the average distance between metal cations decreased while the interlayer spacing gradually increased, in agreement with the experimental data. At the same time, electrons gradually transferred from layer to interlayer anions. As a result, the electrostatic interaction, whole supramolecular interaction, and absolute binding energy value of the system increased, improving system stability. Meanwhile, the average M－O bond length decreased, and the distorted O－M－O angles were weakened to some degree. All of these changes are beneficial to the formation of a stable system, so we conclude that Ni-Al-HT is more stable than Mg-Al-HT.