Theoretical Study on the Swelling Mechanism and Structural Stability of Ni3Al-LDH Based on Molecular Dynamics

Xiaoliang Wang; Leiming Chang; Haonan Zhao; Zhenqiu Yu; Yingkai Xia; Chuanhui Huang; Shaobin Yang; Guoxiang Pan; Shengjie Xia; Yi Liu; Jingxin Fan

doi:10.1021/acsomega.2c06872

Theoretical Study on the Swelling Mechanism and Structural Stability of Ni₃Al-LDH Based on Molecular Dynamics

ACS Omega. 2023 Jan 10;8(3):3286-3297. doi: 10.1021/acsomega.2c06872. eCollection 2023 Jan 24.

Authors

Affiliations

¹ 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.
² School of Mechanical and Electrical Engineering, Xuzhou University of Technology, Xuzhou221111, China.
³ School of Engineering, Huzhou University, Huzhou313000, China.
⁴ College of Chemical Engineering, Zhejiang University of Technology, Hangzhou310014, China.
⁵ CCTEG China Coal Research Institute, Beijing100013, China.

Abstract

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 Ni₃Al-LDH is constructed, and the supramolecular structure, swelling law, stability, and anion diffusion properties of Ni₃Al-LDH are investigated by molecular dynamics theory calculations. The results show that the interlayer water molecules of Ni₃Al-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 Ni₃Al-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^-8 cm²·s^-1.