Unraveling Temperature-Dependent Contact Electrification between Sliding-Mode Triboelectric Pairs

The underlying mechanism on contact electrification (CE) has remained a topic of debate over centuries, and it is argued to be due to electron transfer, ion transfer, and/or even material species transfer. Recently, a previous study shows that CE is dominated by electrons, at least for solid–solid cases. Herein, by using a model detailing the charge transfer between triboelectric surfaces and thermionic emission of electrons via employing a sliding mode Ti–SiO₂ triboelectric nanogenerator (TENG), surface charge decay behavior is scrutinized in lateral-sliding mode during operation at high temperature. The temperature dependence of TENG electric output contributes to characteristic metal–dielectric and dielectric–dielectric CEs, thereby providing further evidence that electrons are the dominating transferred charges in CE. The total surface charge output of the TENG is rationalized as a direct consequence of the coupling of the rate of electron thermionic emission, the charge transfer rate of CE, and the changing rate of the contacted area between the two materials. When the contacting area is larger than the displaced area, the CE between the two materials is the major contributor to measured surface charge. Conversely, the thermionic emission of the exposed surfaces dictates when the contacting area is smaller.