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Control of Micro-and Nanostructure of Layered Double Hydroxides by Hydrothermal Treatment

Published

Author(s)

Keiichiro Maegawa, Fan Zhang, Qiaxian Johnson, Mihaela Jitianu, Tan Wai Kian, Go Kawamura, Atsunori Matsuda, Andrei Jitianu

Abstract

Layered double hydroxides (LDHs) are mixed M(II) and M(III) hydroxides with positively charged lamellar brucite layers and interlayered anions. LDHs attracted significant attention due to their anion and cation-exchange ability, adsorption capacity, and potential applications in drug delivery and catalysis. The properties of LDHs directly correlate with their structures. In this study, we synthesized nickel-aluminum LDHs by the sol-gel method. We investigated the changes in their crystal structure/morphology introduced by hydrothermal treatments that varied from 0 h to 48 h. Based on measured data using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and synchrotron-based small-angle X-ray scattering, we demonstrate that the duration of the hydrothermal treatment can effectively control the micro- and nanostructure of Ni-Al LDHs. We found that the hydrothermal treatment leads to a two-step change in the structure of the LDHs. In the first step, the crystallization occurred during the first 24 hours of hydrothermal treatment, increasing the interlayer width (from 2.28 nm to 2.31 nm) and crystallite size (from 14.2 nm to 50.6 nm). In the second step, the predominant phenomena were stacking, and planar expansion after the crystallization process approached equilibrium. Thus, the layered structure already developed in the first step is further stacked, and the hexagonal platelets characteristic of LDH expands in planner direction. Our study suggests that the duration of the hydrothermal treatment is a crucial factor in the structural evolution of the LDHs and can be used to control the structure of the LDHs for different applications.
Citation
Crystal Growth & Design

Keywords

Microstructure, Layered double hydroxides, structure characterization, small angle scattering

Citation

Maegawa, K. , Zhang, F. , Johnson, Q. , Jitianu, M. , Kian, T. , Kawamura, G. , Matsuda, A. and Jitianu, A. (2023), Control of Micro-and Nanostructure of Layered Double Hydroxides by Hydrothermal Treatment, Crystal Growth & Design, [online], https://doi.org/10.1021/acs.cgd.2c01124, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=935210 (Accessed February 28, 2024)
Created February 23, 2023, Updated March 9, 2023