Linyou Cao, from North Carolina State University, USA, invited by Prof. Yongxing Shen, gave us a talk on August 4, 2015.

Time & Date: 10:00-11:00 am, August 4 (Tuesday) , 2015

Location: Room 415, 4th floor, JI Building

Title:2D Transition Metal Dichalcogenide Materials: Towards Atomic-scale Catalysis and Photonics

Abstract

Two-dimensional (2D) transition metal dichalcogenide (TMDC) materials such as MoS2, WS2, MoSe2, and WSe2 have emerged as a topical area of physical science and engineering.   It is widely believed that these materials bear great potentials to enable new functionalities that cannot be obtained with other material systems.   However, the understanding for the fundamental properties of 2D TMDC materials has remained limited.  This stands as a major challenge for the endeavor of applying these materials to practical devices

In this talk, I will present the new fundamental understanding that we have obtained on the catalytic and optical properties of atomically thin MoS2 films.  Many of the new understanding are unexpected and surprising to some degree.  For instance, we find that monolayer MoS2 provides an excellent catalyst for the hydrogen evolution reaction (HER) with remarkable catalytic activities and stability.  Our results also suggest that the conventional theory, which believes that only the edge site of MoS2 is catalytic active, is likely wrong.  Additionally, we find that the dielectric function of atomically thin MoS2 films is dominated by excitonic effects, instead of the effect of band structures that usually play a dominant role in the dielectric function of conventional materials. Except showing the advance in fundamental understanding, we will show the novel catalytic and photonic devices that we have designed by leveraging on the new scientific advance.

Biography

Cao is an assistant professor in the Department of Materials Science and Engineering at North Carolina State University (NCSU).  He obtained his PhD degree in materials science from Stanford University in 2010 and held a Miller Research Fellowship at the University of California, Berkeley prior to joining the faculty of NCSU in July 2011.  His research work has focused on the photonics and catalysis of 2D TMDC materials.  He received a Young Investigator award from the Army Research Office and a CAREER award from the National Science Foundation, and has coauthored 40+ papers with +2800 citations.