ZnAl–LDH-induced electroactive β-phase and controlled dielectrics of PVDF for a high-performance triboelectric nanogenerator for humidity and pressure sensing applications

Abstract

Layered double hydroxides (LDHs) have been extensively investigated for various applications such as drug delivery, energy storage, catalysis, and luminescence. In this study, an eco-friendly ZnAl–CO₃–LDH–poly(vinylidene fluoride) (ZnAl–LDH–PVDF) composite acting as a triboelectric dielectric material is described. The composite material can realize a high-performance, flexible, and transparent triboelectric nanogenerator (TENG). The strong interactions between ZnAl–LDH and PVDF facilitate the formation of a spontaneous polar β-PVDF phase and enhance the dielectric properties of composite films considerably. The output performance of ZnAl–LDH–PVDF composite-based TENGs with various amounts of ZnAl–LDH was investigated. 20 wt% ZnAl–LDH–PVDF TENG demonstrated an output voltage of ∼230.6 V, current density of ∼5.6 μA cm⁻², and power density of 0.43 mW cm⁻². The pressure- and humidity-dependent outputs of the device enable it to be an effective self-powered pressure and humidity sensor. As a pressure sensor, the device revealed an excellent pressure sensitivity of 13.07 V kPa⁻¹. As a humidity sensor, it exhibited a response of 259.4% in the voltage detection mode. The improved polar β-PVDF phase and dielectric properties of the ZnAl–LDH–PVDF composite make it suitable for high-performance mechanical energy harvesters in self-powered sensor applications.