Synthesis of two-dimensional layered double hydroxides: a systematic overview

Abstract

Two-dimensional (2D) layered double hydroxides (LDH) are classic materials in fundamental research and practical application. 2D LDH have unique structural features, such as high aspect ratio, high specific surface area, quantum confinement in one direction, layered structure, tunable intercalated anions/interlayer spacing/metal-cation compositions, etc., which endow 2D LDH with excellent chemical and physical properties. Since rational production is the first and crucial step towards their utilization, numerous efforts have been devoted to explore innovative and effective methods for their preparation. This review is a comprehensive overview of synthesis methods and aimed to capture the features of different synthesis methods to enable the selection of a suitable method to achieve the desired LDH characteristics. Therefore, we systematically summarized various preparation methods of 2D LDH, including a top-down approach, bottom-up approach, and decomposition-regrowth strategy. Besides, we listed and compared the important parameters relating to both the synthesis process and the obtained products of various synthesis methods, such as the synthesis temperature/pressure, the used device, the utilized reactants, the presence or absence of pre/post-treatment, the yield, the crystallinity and the lateral size and thickness. Finally, some current challenges and further tasks regarding the synthesis of LDH are presented.