Performance Optimization of Liquid-Solid Nanogenerators With Fluorinated Alkyl Self-Assembled Monolayers

Liquid-solid triboelectric nanogenerators (LS-TENGs) based on contact electrification and electrostatic induction effect have garnered significant attention as a promising renewable energy harvesting technology. So far, the LS-TENGs still have relatively low charge density. Here, we developed a tubular structure LS-TENG with high charge density by employing a self-assembled fluoroalkyl layer and grounding water. It was found that the transferred charge of the tubular structure LS-TENG can be enhanced by grounding water, which is likely attributed to the grounded water acquiring more charges from the ground to effectively shield the dielectric surface charges. Then, applying fluorinated modification on silica (SiO₂) surface to enhance surface contact electrification, the tubular LS-TENG generated a high transferred charge of 1.96 µC (charge density of 2.16 mC m^-2), superior to previous LS-TENGs based on contact electrification. The electrical output performance of the tubular LS-TENGs can be precisely regulated by adjusting the motion frequency, swing angle, and liquid properties. Finally, the tubular LS-TENGs successfully realized the parallel connection of multiple devices and powered a hygrothermometer, which exhibits great potential in low-frequency mechanical energy harvesting and self-powered system applications.