Spontaneous Wetting Induced by Contact‐Electrification at Liquid–Solid Interface

Abstract

Wettability significantly influences various surface interactions and applications at the liquid‐solid interface. However, our understanding is complicated by the intricate charge exchange occurring through contact electrification (CE) during this process. The understanding of the influence of triboelectric charge on wettability remains challenging, especially due to the complexities involved in concurrently measuring contact angles and interfacial electrical signals. Here, we investigate the relationship between surface charge density and change of contact angle of dielectric films after contact with water droplets. We observe that the charge exchange when water spared lead to a spontaneous wetting phenomenon, which is termed as the contact electrification induced wetting (CEW). Notably, our results demonstrate a linear dependence between the change of contact angle (CA) of the materials and the density of surface charge on the solid surface. Continuous CEW tests show that not only the static CA but also the dynamics of wetting are influenced by the accumulation charges at the interface. The mechanism behind CEW involves the redistribution of surface charges on a solid surface and dipolar water molecules within liquid. This interaction results in a decrease in interface energy, leading to a reduction in the CA. Ab initio calculations suggest that the reduction in interface energy may stem from the enhanced surface charge on the substrate, which strengthens the hydrogen bond interaction between water and the substrate. These findings have the potential to advance our understanding of CE and wetting phenomena, with applications in energy harvesting, catalysis, and droplet manipulation at liquid‐solid interfaces.This article is protected by copyright. All rights reserved

Elastic Droplet-Based Magnetoelectric Generator for High-performance Energy Collection

“…Wu et al reported a charge trapping-based electricity generator (CTEG) for harvesting energy from irregular water droplets, which produced a negative charge density of 1.8 mC/m 2 . However, the methods mentioned above are inevitably limited by the saturation density of the liquid/solid interfaces and the inefficient utilization of surface charges, ,, and their relatively low current output makes them difficult to use in practical applications.…”