Boron Nitride Nanosheet Dispersion at High Concentrations

There is an increasing demand for boron nitride nanosheets (BNNSs) for a range of applications such as advanced composite materials, ion/gas selective membranes, and energy storage. These applications require stable, high-concentration BNNS dispersions as a precursor, which is a challenge because BNNSs do not disperse easily. We report a simple, yet efficient, mechanochemical exfoliation technique to prepare functionalized BNNSs with excellent dispersibility in water and organic solvents. The resultant amino-modified BNNSs (BNNS-NH₂) are stable in ethanol for 3 months at an unprecedented high concentration of 46 ± 2 mg/mL. We provide insights into the dispersibility mechanism for amino- and hydroxyl-functionalized BNNSs. High-concentration BNNS dispersions enable a facile painting method that can coat a uniform, insulating, and antioxidant BNNS layer on arbitrary surfaces. In addition, different functional groups enhance the selectivity of different ions of the functionalized BNNS membranes for water purification and other ion separation applications. These stable, high-concentration BNNS dispersions make many exciting applications possible.