◎ Title : Simple Chemical Reactions and Chemical Properties of Graphene
◎ Speaker: Prof. Sunmin Ryu (Dept. of Applied Chemistry, Kyung Hee Univ.)
◎ Date & Time : 6. 15(화) 16:30 - 18:00
◎ Place : 신소재공학과 제2세미나실, W1-1 Building
◎ Abstract :
Simple Chemical Reactions and Chemical Properties of Graphene
Atom-thick graphene membrane holds substantial potential for applications in future molecular-scale integrated electronics, transparent conducting membranes, nanocomposites, etc. To realize this potential, chemical properties of graphene need to be understood and functionalization toolkits are also required. To meet this need, surface chemistry of graphene has been explored by Raman spectroscopy, AFM and STM scanning probes. In the first part of the talk, two chemical reactions of graphene will be presented. Hydrogenation, the simplest basal plane functionalization, is highly reversible and strongly dependent on the thickness of graphene in the rate. Graphene sheets can be locally hydrogenated with a high spatial resolution. Thermal oxidation also proceeds at a higher rate for single layer than double layer graphene and triple layer graphene behaves like bulk graphite. The second part of the talk will illustrate the influence of underlying silicon dioxide substrates and ambient gases on properties of graphene. Raman spectroscopy shows that freestanding graphene is essentially charge-neutral implying that the “usual” hole-doping in supported graphene is mediated by oxide substrates. An STM study reveals that thermal annealing generates out-of-plane deformation of nanometer-scale wavelength and distortion in sp2 bonding on an atomic scale. Graphene deformed by annealing is found to be chemically active enough to bind molecular oxygen, which leads to a strong hole-doping. A possible form of oxides will be discussed.