Piezoelectric boron nitride nanosheets for high performance energy harvesting devices

Highlights: • We report a high-performance hybrid piezo/triboelectric nanogenerator utilizing few-layered hexagonal boron nitride nanosheets . • The BNNS-PDMS/PA6 PTEG demonstrates ultrahigh power density and stability with superior energy conversion efficiency. • The enhanced performance originates the synergy of the piezoelectric effects and the increased negative triboelectric properties of BNNS-PDMS composite membranes. The hexagonal boron nitride nanosheets (BNNSs) are one of the 2-dimensional(2D) materials, and have been explored for their applications in nanoelectronics etc, owing to their unique properties. Here, BNNSs are utilized to develop a high-performance hybrid piezo/triboelectric nanogenerator (PTEG). BNNSs of a few percentages in weight are incorporated into polydimethylsiloxane (PDMS) to form composites that are able to produce piezoelectric voltages up to ~ 5.4 V with $d_{33}$ ~ 12 pC/N. A PTEG composed of BNNS-PDMS and polyamide-6 (PA6) membranes ($20\times 20{\mathrm{mm}}^2$) demonstrates a current density of ~ 230 mA $m^{-2}$, an output voltage of ~ 1870 V and a maximum power density of ~ 103.7 $W{m}^{-2}$, more than three times higher than those of the control PDMS/PA6 nanogenerator. Electric polarization of the BNNS-PDMS membranes can further enhance the output of PTEGs. Detailed investigation reveals that the dramatically enhanced performance originates from the synergy of piezoelectric effect of BNNSs and increased electron affinity of BNNS-PDMS membranes, demonstrates the excellent potential of BNNS-based PTEGs.