PHYSICS/BK21 SEMINAR[09.11.25]

                                                               
                   “Functionalization and Chemical
                  Properties of Graphene”
  
Ø ♦ Speaker :  Prof. Sunmin Ryu [Kyung Hee University]  
Ø ♦ Place : Physics Seminar Room (Science Bldg, 3-201)
Ø ♦ Date & Time : Nov, 25(Wed)  3:00  ~  4:00 pm

Abstract
  
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 t o  a
strong hole-doping. A possible form of oxides will be discussed.
  
  
          Contact Person : Prof. Nam Ki Lee (054-279-2097, nklee@postech.ac.kr)