Ultrasound Mediates Discharging of Hexagonal Boron Nitride Nanoflakes in Liquid Conditions

Two-dimensional hexagonal boron nitride has been discovered for piezoelectric property in response to mechanical deformation. However, the quantitative measurement of piezoelectric effects in hexagonal boron nitride and its applicability are still explored. Here, we demonstrated the synthesis of boron nitride nanoflakes by mechanochemical exfoliation and employed the electrochemical method to quantitatively evaluate the piezoelectric performance of the nanoflakes deposited on carbon paper substrate under ultrasonic circumstances. The charge was reached up to 69.29 μC calculated from cyclic voltammogram at 30 mV/s sweep rate under 2.976 MPa induced by ultrasound. The net increased charge was 49.54 μC/mm 2 at 2.976 MPa. The output current was measured up to ~597 pA/mm 2 and positive shift of output voltage shifted from -600 mV to -450 mV. In addition, we observed that the piezoelectric performance linearly increased with pressure induced by ultrasound. Ultrasound-mediated boron nitride nanoflakes paves the new routes for applications of energy and biomedical field.