Homogeneous Nanosheets on Microfiber-Assembled Boron Nitride Foams for Oil/Water Separation

Boron nitride (BN) foam, characterized by its low density, chemical inertness, hydrophobicity, and lipophilicity, has shown considerable promise for oil/water separation. Herein, a hydrophobic-oleophilic DB-BN foam is prepared through the in situ growth of BN nanosheets on microfibers by impregnating a pre-pyrolyzed BN microfibrous foam into a dimethylformamide-boric acid (DMF–BA) solution, followed by high-temperature pyrolysis. The resulting DB-BN foam, with a density of ∼0.039 g/cm3, displays significantly enhanced surface roughness while preserving structural integrity compared with the pre-pyrolyzed BN foam. Moreover, it exhibits superior superhydrophobicity with a high water contact angle of 155.31°. The unique microstructure and thermal stability endow the DB-BN foam with high adsorption capacities for various oil solvent, reaching 11.7 to 33.5 times its own weight, as well as excellent recyclability. This work not only presents an effective strategy for the homogeneous modification for BN-based materials but also opens up their potential applications in advanced oil/water separation.