2D intercalated charge confinement and surface modification in a montmorillonite-based composite for an anti-bacterial and biodegradable self-powered sensor

Abstract

Although triboelectric nanogenerators (TENGs) are an eco-friendly method for converting waste mechanical energy into electrical energy, the materials used in TENGs often include high electron affinity substances that are not biodegradable due to the low electron affinity and dielectric constant of biodegradable alternatives. In this paper, we report a method to enhance charge trapping and the dielectric constant through a novel intercalation process that uses newly synthesized quaternary ammonium compounds with two-dimensional layered montmorillonite (MMT), a naturally occurring silicate mineral, along with surface modification using fluorine. This approach improves charge confinement within the interlayered silicate structure during electrostatic induction. By employing a newly designed quaternary ammonium compound, we successfully reduce intercalation costs, increase the interlayer spacing of MMT to improve dispersion, and enhance electron affinity. The surface of the intercalated MMT is further modified using fluorosilane. The modified MMT is then incorporated into the biodegradable polymer PBAT (Polybutylene Adipate Terephthalate), which improves the efficiency of the TENG. Experimental results show that the charge-trapping effect of the layer-by-layer MMT structure, combined with increased charge confinement from the expanded interlayer spacing, leads to greater charge storage and improved charge transport efficiency. PBAT/OMMT@F13 at 0.4 wt%, exhibits the highest charge-trapping performance and energy-conversion efficiency due to the charge confinement and electron-withdrawing effect, producing approximately 3.9 times higher voltage and 2.4 times greater output current than pristine PBAT. Due to the antibacterial activity of quaternary ammonium and the hydrophobicity introduced by fluorine, it also functions effectively as a hygienic electronic device and antibacterial film in a wearable TENG-based sensor system.