Spring Design of Triboelectric Nanogenerator with MXene-Modified Interface for Fluid Energy Harvesting and Water Level Monitoring.

The introduction of two-dimensional materials with high capacitance that are dielectric into the triboelectric interface is critical for the development of a highly efficient triboelectric nanogenerator (TENG) due to its excellent electrical conductivity and versatile surface chemistry. This paper reports a spring-structured multilayer TENG (S-TENG), where a NbCT MXene-PVDF composite was chosen as the triboelectric electrode for increasing the dielectric and surface charge density. The intense electrostatic interaction of the strong hydrogen bonds between anions on the MXene surface and hydrogen atoms of PVDF chains not only creates a dipole in responding to the applied electric field but also promotes the formation of a piezoelectric phase and induces a strong interface coupling effect. Consequently, an output power enhancement of 300% was shown in comparison with pure PVDF, and a spring-like design with a multilayer structure further increases the space utilization and contact area and presents an output voltage of 420 V, a current density of 1.47 mA/m, and a maximal output power density of 619 mW/m. In addition, the as-prepared S-TENG can serve as both a fluid energy harvester on an urban river and a real-time monitor to realize the automatic alarm of water level warning.