Fast\nSolid-Phase Exfoliation of Layered Double Hydroxides\nwith Tunable Functionalization

Two-dimensional\n(2D) layered double hydroxides (LDHs) with adjustable\ncompositions and structure have been promising candidates for various\ndomains, including catalysis, water treatment, and energy storage.\nTo unlock their full potential, there is a strong demand for versatile\nand effective exfoliation techniques capable of generating diverse\ntypes of 2D LDHs. However, the conventional liquid-phase exfoliation\nmethods typically rely on toxic solvents and face challenges with\nagglomeration and restacking. Herein, a series of LDHs, including\nCoAl-LDH, MgAl-LDH, ZnAl-LDH, and NiFe-LDH, have been successfully\nexfoliated into nanosheets using a solid-phase exfoliation technique.\nMeanwhile, surface functional groups and defects are introduced into\nthe exfoliated LDHs. The incorporation of surface functional groups\nimproves the homogeneity and aqueous dispersion stability of LDH nanosheets,\nenabling them to be stably stored for over six months while remaining\nredispersible and processable even after freeze-drying. Furthermore,\nthe induced defects alter the electronic structure of the LDH nanosheets,\ngenerating more active sites that enhance their electrocatalytic performance.\nThese advantages contribute to the superior OER activity of the exfoliated\nNiFe-LDH nanosheets with an ultralow overpotential of 258 mV at 10\nmA cm<sup>–2</sup>. This work highlights the potential of solid-phase\nexfoliation as an efficient, environmentally friendly, and scalable\nmethod for the preparation and functionalization of 2D LDHs.