Study of contact electrification by the synchrotron-based X-ray photoelectron spectroscopy

Lo Yueh Chang^1,2*, Yu-Xun Chen¹, Chia-Hao Chen¹, Zhen Wen², Xuhui Sun²

¹nano science, National Synchrotron Radiation Research Center, Hsin-chu, Taiwan
²Institute of Functional Nano and Soft Materials, Soochow University, Suzhou, China

* Presenter:Lo Yueh Chang, email:chang.loyueh@nsrrc.org.tw

Contact electrification is a general phenomenon while two neutral materials touching each other. After the touching process, the contacting surface is electrically charging with opposite polarities and the equally total charge. In the past two decades, it is developed to harvest the mechanical energy by human activities naming as triboelectric nanogenerators (TENGs).
Although the contact electrification was found hundreds or thousand years ago, its mechanism is a little known. Hypothesized main mechanism of surface charge formation is proposed that the electron, ion, or materials specie transfer onto the surface which is proved and working on boundary situations. It is under debate due to the lack of fundamental understand. In order to realize the mechanism during contact electrification process, we systematically monitored the contact-separation process by the in-situ measurement through synchrotron-based X-ray photoelectron spectroscopies (SR-XPS), providing a higher surface-sensitivity. The entire process is in ultra-high vacuum condition to avoid the air and adsorbates contamination. The SR-XPS result indicates the materials transfer is changed with contact-separation period times. This evidence is related with I-V performance and we propose a mechanism for contact electrification.

Keywords: contact electrification, triboelectric nanogenerators (TENGs), mechanism