Dynamic behavior of tunneling triboelectric charges in two-dimensional materials

Although the research history of triboelectrification has been more than 2000 years, there are still many problems to be solved so far.The use of scanning probe microscopy provides an important way to quantitatively study the transfer, accumulation, and dissipation of triboelectric charges in the process of triboelectrification. Two-dimensional materials are considered to be key materials for new electronic devices in the post-Moore era due to their atomic-scale size advantages. If the electrostatic field generated by triboelectrification can be used to replace the traditional gate electrostatic field, it is expected to simplify the structure of two-dimensional electronic devices and reconfigure them at any time according to actual needs. Here, we investigate the triboelectrification process of various two-dimensional materials such as MoS_(2), WSe_(2),and ZnO. Different from traditional bulk materials, after two-dimensional materials are rubbed, the triboelectric charges generated may tunnel through the two-dimensional materials to the underlying substrate surface. Because the tunneling triboelectric charge is protected by the twodimensional material, its stable residence time on the substrate surface can reach more than 7 days, which is more than tens of minutes for the traditional triboelectric charge. In addition, the electrostatic field generated by the tunneling triboelectric charge can effectively regulate the carrier transport performance of two-dimensional materials, and the source–drain current of the field effect device regulated by the triboelectric floating gate is increased by nearly 60 times. The triboelectric charge tunneling phenomenon in two-dimensional materials is expected to be applied in the fields of new two-dimensional electronic devices and reconfigurable functional circuits.

Method for the measurement of triboelectric charge transfer at solid–liquid interface

Triboelectrification between a liquid and a solid is a common phenomenon in our daily life and industry.Triboelectric charges generated at liquid/solid interfaces have effects on energy harvesting,triboelectrification-based sensing,interfacial corrosion,wear,lubrication,etc.Knowing the amount of triboelectric charge transfer is very useful for studying the mechanism and controlling these phenomena,in which an accurate method is absolutely necessary to measure the triboelectric charge generated at the solid–liquid interface.Herein,we established a method for measuring the charge transfer between different solids and liquids.An equipment based on the Faraday cup measurement was developed,and the leakage ratio(r_(l))was quantified through simulation based on an electrostatic field model.Typical experiments were conducted to validate the reliability of the method.This work provides an effective method for charge measurement in triboelectrification research.