中國科學技術大學李震宇教授做客第254期化苑講壇
報告題目：Mechanisms of Graphene Growth and Cutting
報 告 人 ：李震宇教授
報告時間：2017年5月5日（周五）下午14:30
報告地點：化學樓二樓一號會議室
邀 請 人 ：楊利明教授
報告人簡介：
李震宇，男，中國科學技術大學教授、合肥微尺度物質科學國家實驗室研究員、博士生導師。1999和2004年分別獲得中國科學技術大學物理學學士和物理化學博士學位。2004-2007年先后在美國馬里蘭大學和加州大學歐文分校從事博士后研究。2006年入選全國百篇優秀博士學位論文作者，2008年入選教育部新世紀優秀人才支持計劃，2011年獲中國科學院盧嘉錫青年人才獎，2012年獲得國家自然科學基金委首屆優秀青年科學基金項目資助，2015年獲中國化學會青年化學獎。研究領域為理論與計算化學，主要通過電子結構計算與分子模擬來研究材料物性和生長反應機理。在包括Phys. Rev. Lett.、JACS、Angew. Chem. Int. Ed.在內的國際學術期刊上發表論文120余篇，SCI引用3600余次，H因子為31。
報告內容：
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.
