Rapid Exfoliation of Hexagonal Boron Nitride in a Less-Volatile Co-Solvent with a High Dispersion Concentration

Hexagonal boron nitride nanosheets (BNNSs), are among the most prominent layered two-dimensional (2D) nanomaterials due to their superior thermal, electrical, and dielectric properties. However, their strong interlayer bonding limits efficient exfoliation into few-layer structures. In this study, a mixed-solvent strategy based on 1-cyclohexyl-2-pyrrolidone (CHP) and deionized water was developed for rapid and scalable production of BNNSs via sonication-assisted liquid-phase exfoliation (LPE). A CHP/water ratio of 1:20 enabled stable dispersion of exfoliated hBN at a concentration of 1.05 mg/mL, with 56% of the starting material delaminated. Atomic force microscopy (AFM) analysis revealed that 16.8% of the exfoliated product consisted of nanosheets thinner than five layersafter a fast exfoliation. In contrast, exfoliation using IPA/water (3:7) under identical conditions yielded predominantly thick, stacked hBN structures. Spectroscopic and microscopic analyses, including UV–Vis, FTIR, XRD, and Raman, confirmed effective delamination and structural preservation of CHP-exfoliated BNNSs. These results highlight the critical role of solvent composition and demonstrate the superior performance of CHP-based systems as a co-solvent for time-efficient exfoliation. This scalable and safer approach can be adapted for other layered materials and holds strong potential for expanding the use of BNNSs in advanced technological applications.