Morphological control synthesis of layered double hydroxides for energy applications

Abstract

Layered Double Hydroxides (LDHs), a versatile class of anionic clays, offer unique advantages, such as adjustable metal cation ratios, expandable interlayer spaces, and surface modifiability, which critically influence their functionality in energy storage and conversion technologies. However, the structural parameters of LDHs, including morphology, particle size, and crystallinity, are heavily dependent on synthesis methods and reaction conditions. This review systematically explores the intricate relationships between synthesis approaches, such as co-precipitation, hydrothermal synthesis, sol-gel methods, electrochemical deposition, calcination-recovery, exfoliation, and microwave-assisted synthesis, and the resulting LDH structures. Emphasis is placed on tailoring LDH morphologies to meet the demands of energy applications, such as enhancing charge storage in supercapacitors, optimizing ion diffusion in batteries, and improving catalytic activity for water-splitting technologies. Key reaction parameters, including pH, temperature, reaction duration, and the role of additives and templates, are analyzed for their impact on LDH characteristics. Additionally, advanced characterization techniques, such as X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray absorption spectroscopy (XAS), Inductively coupled plasma (ICP), and thermogravimetric analysis (TGA), are reviewed for their role in understanding LDH structures. Finally, the challenges of cost-effectiveness and scalability are discussed, highlighting future research directions that aim to optimize LDH synthesis for practical energy applications.