Wang Xiaoliang, Chang Leiming, Zhao Haonan, Yu Zhenqiu, Xia Yingkai, Huang Chuanhui, Yang Shaobin, Pan Guoxiang, Xia Shengjie, Liu Yi, Fan Jingxin
College of Materials Science and Engineering, Key Laboratory of Mineral High Value Conversion and Energy Storage Materials of Liaoning Province, Geology and Mineral Engineering Special Materials Professional Technology Innovation Center of Liaoning Province, Liaoning Technical University, Fuxin123000, China.
School of Mechanical and Electrical Engineering, Xuzhou University of Technology, Xuzhou221111, China.
ACS Omega. 2023 Jan 10;8(3):3286-3297. doi: 10.1021/acsomega.2c06872. eCollection 2023 Jan 24.
layered double hydroxide (LDH) as a kind of 2D layer material has a swelling phenomenon. Because swelling significantly affects the adsorption, catalysis, energy storage, and other application properties of LDHs, it is essential to study the interlayer spacing, structural stability, and ion diffusion after swelling. In this paper, a periodic computational model of NiAl-LDH is constructed, and the supramolecular structure, swelling law, stability, and anion diffusion properties of NiAl-LDH are investigated by molecular dynamics theory calculations. The results show that the interlayer water molecules of NiAl-LDH present a regular layered arrangement, combining with the interlayer anions by hydrogen bonds. As the number of water molecules increases, the hydrogen bond between the anion and the basal layer gradually weakens and disappears when the number of water molecules exceeds 32. The hydrogen bond between the anion and the water molecule gradually increases, reaching an extreme value when the number of water molecules is 16. The interlayer spacing of NiAl-LDH is not linear with the number of water molecules. The interlayer spacing increases slowly when the number of water molecules is more than 24. The maximum layer spacing is stable at around 19 Å. The interlayer spacing, binding energy, and hydration energy show an upper limit for swelling: the number of water molecules is 32. When the number of interlayer water molecules is 16, the water molecules' layer structure and LDH interlayer spacing are suitable for anions to obtain the maximum diffusion rate, 10.97 × 10 cm·s.
层状双氢氧化物（LDH）作为一种二维层状材料存在膨胀现象。由于膨胀会显著影响LDH的吸附、催化、储能等应用性能，因此研究其膨胀后的层间距、结构稳定性和离子扩散至关重要。本文构建了NiAl-LDH的周期性计算模型，采用分子动力学理论计算研究了NiAl-LDH的超分子结构、膨胀规律、稳定性和阴离子扩散性质。结果表明，NiAl-LDH层间水分子呈规则的层状排列，通过氢键与层间阴离子结合。随着水分子数量增加，当水分子数量超过32时，阴离子与基层之间的氢键逐渐减弱并消失。阴离子与水分子之间的氢键逐渐增加，在水分子数量为16时达到极值。NiAl-LDH的层间距与水分子数量并非呈线性关系。当水分子数量超过24时，层间距缓慢增加。最大层间距稳定在19 Å左右。层间距、结合能和水化能显示出膨胀的上限：水分子数量为32。当层间水分子数量为16时，水分子的层结构和LDH层间距适合阴离子获得最大扩散速率，即10.97×10 cm·s 。
