中国科学技术大学李震宇教授做客第254期化苑讲坛

报告题目：Mechanisms of Graphene Growth and Cutting

报 告 人 ：李震宇教授

报告时间：2017年5月5日（周五）下午14:30

报告地点：化学楼二楼一号会议室

邀 请 人 ：杨利明教授

报告人简介：

李震宇，男，中国科学技术大学教授、合肥微尺度物质科学国家实验室研究员、博士生导师。1999和2004年分别获得中国科学技术大学物理学学士和物理化学博士学位。2004-2007年先后在美国马里兰大学和加州大学欧文分校从事博士后研究。2006年入选全国百篇优秀博士学位论文作者，2008年入选教育部新世纪优秀人才支持计划，2011年获中国科学院卢嘉锡青年人才奖，2012年获得国家自然科学基金委首届优秀青年科学基金项目资助，2015年获中国化学会青年化学奖。研究领域为理论与计算化学，主要通过电子结构计算与分子模拟来研究材料物性和生长反应机理。在包括Phys. Rev. Lett.、JACS、Angew. Chem. Int. Ed.在内的国际学术期刊上发表论文120余篇，SCI引用3600余次，H因子为31。

报告内容：

Graphene is an important material with unique properties and accordingly many potential applications. A promising way to produce high-quality wafer-size graphene is chemical vapor deposition (CVD) on metal surfaces. To improve the sample quality, it is important to understand the atomic details during graphene CVD growth. At the same time, to make devices, cutting graphene into different shapes is frequently required. In this talk, we focus on theoretical studies of the growth and cutting mechanisms. On Ir(111) surface, a universal lattice mismatch induced nonlinear growth mechanism is revealed via first principles calculations and kMC simulations. On Cu(111) surface, a significant carbon adsorption/diffusion induced surface relaxation characterized by the formation of bridging-metal (BM) structures is predicted. Dimer is found to be the growth feeding species, which leads to the experimentally observed diffusion-limited growth behavior. In CVD growth of graphene, hydrogen plays an important role and the dominant kinetic pathways are also determined by kMC simulations. Oxidative cutting of graphene proceeds with an unzipping mechanism, while graphene cutting by metal nanoparticles has a Pac-Man mechanism.