One-step environmentally friendly exfoliation and functionalization of hexagonal boron nitride by β-cyclodextrin-assisted ball milling

Hexagonal boron nitride nanosheets (BNNs) are gaining much attention owing to their extraordinary performance; however, difficulties remain in achieving their large-scale preparation and dispersion at high concentration in solvents. A facile yet efficient β-cyclodextrin-assisted mechanochemical exfoliation method is proposed to exfoliate and functionalize hexagonal boron nitride (h-BN). The β-cyclodextrin-assisted ball milling process gave a high yield of 60%, with the resultant BNNs being covalently grafted with hydroxyl, and well dispersed in water and other solvents. The concentration of the hydroxyl-functionalized boron nitride nanosheets (OH-BNNs) reached 3 mg/mL, and was stable for several weeks. Next, we fabricated a membrane based on the resulting OH-BNNs to effectively capture Congo red dye. This work not only offers an environmentally friendly, efficient, solvent-less and extremely cost-effective scalable production method, but also assists in our understanding of the mechanism of exfoliation and functionalization in other layered materials.