Fast Solid-Phase Exfoliation of Layered Double Hydroxides with Tunable Functionalization

Two-dimensional (2D) layered double hydroxides (LDHs) with adjustable compositions and structure have been promising candidates for various domains, including catalysis, water treatment, and energy storage. To unlock their full potential, there is a strong demand for versatile and effective exfoliation techniques capable of generating diverse types of 2D LDHs. However, the conventional liquid-phase exfoliation methods typically rely on toxic solvents and face challenges with agglomeration and restacking. Herein, a series of LDHs, including CoAl-LDH, MgAl-LDH, ZnAl-LDH, and NiFe-LDH, have been successfully exfoliated into nanosheets using a solid-phase exfoliation technique. Meanwhile, surface functional groups and defects are introduced into the exfoliated LDHs. The incorporation of surface functional groups improves the homogeneity and aqueous dispersion stability of LDH nanosheets, enabling them to be stably stored for over six months while remaining redispersible and processable even after freeze-drying. Furthermore, the induced defects alter the electronic structure of the LDH nanosheets, generating more active sites that enhance their electrocatalytic performance. These advantages contribute to the superior OER activity of the exfoliated NiFe-LDH nanosheets with an ultralow overpotential of 258 mV at 10 mA cm^-2. This work highlights the potential of solid-phase exfoliation as an efficient, environmentally friendly, and scalable method for the preparation and functionalization of 2D LDHs.