演讲人Speaker：   Xianghua Kong

题目Title: 2D photocatalysts on III-Nitrides nanowires

时间Date：2019年9月7日Time：11:00-11:30

地点Venue：G栋514室

内容摘要Abstract：

Hydrogen generation via photoelectrochemical (PEC) water splitting is an appealing approach for conversion of solar energy into valueaddedchemical fuels. PEC requiresphotocatalysts to function and low dimensionalphotocatalystshave received tremendous attention.Weproposeasuper-heterostructureconsistingoflow-cost, large-area Si wafer,defect-free GaN nanowiresandnoble-metal-free MoS2,andexcitingly,thissuper-heterostructuredemonstratedoutstanding photocatalytic performance.Itiswellunderstoodnowthatthissetuptakesfulladvantageoftheirlowdimensionalnature,wheretheGaNnanowirearrayonSiwaferworksforlight harvesting,chargecarrierseparationandtransfer,whileMoS2playstheroleofprotonreduction. This super-heterostructure is a general concept and we have already transferred this idea to CO2 reduction as well as nitrogen fixation. And this concept is quite suitable to be further explored and realized by Data mining and Machine learning which we are working on.

We further report adirect, systematic and general density functional theory scheme to quantitatively predict band edge shifts and their microscopic origins for aqueous 2D photocatalyst, where thousands of atoms or more are able to be involved. This scheme is indispensable to correctly calculate the electronic structure of 2D photocatalyst in the presence of water, which is demonstrated in aqueous MoS2, GaS, WS2, InSe and WSe2.It is found that the band edge of 2D photocatlysts are not rigidly shifted due to water as reported in previous studies of aqueous systems. Specifically, the CBM shift is quantitatively explained by geometric deformation, water dipole and charge redistribution effect while the fourth effect, i.e. interfacial chemical contact, is revealed in the VBM shift. Our work paves the way to design 2D materials in general as low-cost and high-efficiency photocatalysts. 

个人简介(About the speaker):

Xianghua Kong, Post-Doctoral Researcher, Center for the Physics of Materials, Department of Physics, McGill University, Montreal, Canada. She received her PhD in Department of Physics, Renmin University of China in 2016. She worked as a collaboratedstudentinProf. Hong Guo’s group inMcGill Universityfrom 2012 to 2016. Her research interest lies infunctional materials, large scaleDFTsimulationsincluding solid/liquid interface, AFM & STM simulation andtwistronics, and data-driven applications in material science. Till now, she has published 21 papers in influential journals such as Energy & Environmental Science, Nature communications, Cell-Chem, Cell-iScience, Advanced Materials, and AngewandteChemie as well as a book chapter on artificial photosynthesis. According to Google Scholar, her publications have been cited more than 2400 times, h-index 12.