Triboelectric Nanogenerator as a Probe for Measuring the Charge Transfer between Liquid and Solid Surfaces

The phenomenon of triboelectricity involves the flow of charged species across an interface, but conclusively establishing the nature of the charge transfer has proven extremely difficult, especially for the liquid–solid cases. Herein, we developed a self-powered droplet triboelectric nanogenerator (droplet-TENG) with spatially arranged electrodes as a probe for measuring the charge transfer process between liquid and solid interfaces. The information on the electric signal on spatially arranged electrodes shows that the charge transfer between droplets and the solid is an accumulation process during the dropping and that the electron is the dominant charge-transfer species. Such a droplet-TENG showed a high sensitivity to the ratio of solvents in the mixed organic solution, and we postulated this is due to the possibility of generation of a hydrogen bond, affecting the electric signal on the spatially arranged electrodes. This work demonstrated a chemical sensing application based on the self-powered droplet triboelectric nanogenerator.