报告题目：The Balance between Surface Electron Transfer and Electrostatic Discharge: An Insight into Triboelectric Effect
报告人：Prof. Yunlong Zi，(Assistant Professor, The Chinese University of Hong Kong (CUHK))
Triboelectric effect which was discovered from Ancient Greek Era is very common in our daily life. This ancient phenomenon has been recently developed to be triboelectric nanogenerator (TENG) for high-efficiency mechanical energy harvesting from ambient environment. The triboelectric surface charge density is one of the most important parameters in TENG, which has quadratic relation with the output power. It has been understood that this surface charge density is mainly determined by balance of contact electrification and the discharge effects, however, the mechanisms are still not very clear. We have conducted studies on the both effects in the past a few years. Through the study on the thermionic emission behaviors of surface charge, we hypothesized the surface electron transfer mechanism for contact electrification, with the proposed electron cloud – potential well model. Through the simulations on the potential and electric field distributions, we predicted the electrostatic breakdown effects as the major discharge mechanism, which universally exists in all modes of TENGs. Further, we have experimentally demonstrated the breakdown phenomena and the corresponding TENG output behaviors. These studies will not only greatly enhance our understandings on the triboelectric effect, but also facilitate the optimization of the TENG designs to promote the energy output performance.
Prof. Yunlong Zi is an Assistant Professor in Department of Mechanical and Automation Engineering at the Chinese University of Hong Kong. Dr. Zi received his Ph.D. in Physics from Purdue University in 2014; his Bachelor of Engineering in Materials Science and Engineering from Tsinghua University in 2009. Before joining CUHK, he worked as a Postdoctoral Fellow at Georgia Institute of Technology during 2014-2017. His current research interests mainly focus on high-efficiency mechanical energy harvesting through triboelectric nanogenerators (TENG), TENG triggered high-voltage applications, and self-powered systems. As the 1st author, his research studies have been published in top-notch journals, including Nature Nanotechnology, Nature Communications, Advanced Materials, Nano Letters, ACS Nano, Nano Energy, and etc. He was honored as the winner of MRS Postdoctoral Award by Materials Research Society in 2017, as the first recipient from Georgia Tech; the Emerging Investigators by Journal of Materials Chemistry C in 2018; and one of “5 students who are transformation makers” as highlighted in Purdue homepage in 2013.