Water Adsorption and Reactions on Metal and Graphene Surfaces Studied by STM

报告题目： Water Adsorption and Reactions on Metal and Graphene Surfaces Studied by STM 报告人：冯小峰（UC Berkeley）报告时间： 2013年9月4日（周三）上午10：00 报告地点：清华-富士康纳米科技研究中心四楼报告厅摘要： Molecular-level understanding of the chemical processes involved in water adsorption on metal and other surfaces is important in the fields of wetting, corrosion, catalysis, and electrochemistry. Here I would like to present a series of studies on the adsorption and reactions of water on metal and graphene surfaces using scanning tunneling microscopy (STM). At low coverage, water adsorbs on Pd(111) surface in the form of isolated molecules, which diffuse by hopping to nearest neighbor sites. Upon collision, they form water clusters (dimers, trimers, tetramers and so on), of which the mobility is increased by several orders of magnitude than monomers. As coverage increases, water film growth starts by the formation of flat hexamer clusters and then larger networks of linked hexagons with a honeycomb structure, following a two-dimensional (2D) ice rule. Water adsorption on epitaxial graphene on Ru(0001) substrate was also studied. We found that the graphene line defects are extremely fragile towards chemical attack by water, which splits the graphene into numerous fragments at temperatures as low as 90 K, followed by water intercalation under the graphene. This process resulted in many graphene flakes that were displaced onto the first graphene layer on Ru. The superlubric sliding behavior and electronic screening effect of these flakes were also investigated. 联系人：姜开利 96017