Synthesis of boron nitride nanosheets with a few atomic layers and their gas-sensing performance

We report a successful synthesis of hexagonal boron nitride (h-BN) nanosheets with a few atomic layers by a facile yet efficient solvothermal method at the relatively low temperature. After identifying the pure h-BN phase by the X-ray diffraction, the ultrathin BN nanosheets were systematically characterized by field-emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS) element mapping and high-resolution transmission electron microscopy (HRTEM). We find that the h-BN nanosheet has a nearly transparent morphology with a thickness of ~1.36 nm (four atomic layers) and shows dozens of square microns in area. We test the gas-sensing properties of the ultrathin h-BN nanosheets towards ethanol and NH₃, and find that the fabricated gas sensors show a fast response and excellent repeatability to ethanol at optimal operating temperature of 300 ^oC.