AVS 52nd International Symposium
    Nanometer-Scale Science and Technology Friday Sessions
       Session NS-FrM

Paper NS-FrM4
Carbon Nanosheets--A Sub-nanometer Two-dimensional Carbon Nanostructure

Friday, November 4, 2005, 9:20 am, Room 210

Session: Nanotube Processing and Properties
Presenter: M.Y. Zhu, College of William and Mary
Authors: M.Y. Zhu, College of William and Mary
J.J. Wang, College of William and Mary
X. Zhao, College of William and Mary
R.A. Outlaw, College of William and Mary
B. French, College of William and Mary
D.M. Manos, College of William and Mary
B.C. Holloway, College of William and Mary
Correspondent: Click to Email
In this paper, we report a sub-nanometer scaled two-dimensional carbon nanostructure--Carbon nanosheets (CNS) by radio-frequency plasma enhanced chemical vapor deposition (RF-PECVD). CNS were synthesized from mixed gases of methane (CH@sub 4@) and hydrogen (H@sub 2@) on various substrates, including Si, SiO@sub 2@, Al@sub 2@O@sub 3@, Mo, Zr, Ti, Hf, Nb, W, Ta, Cu and 304 stainless steel, without any catalyst or substrate pre-treatment. SEM, HRTEM, SAD, Raman spectroscopy, XRD, XPS and AES, were used to characterize the morphology and structure properties of the CNS. The results showed that CNS consist of graphene layers, oriented nearly vertically to the substrates. Typical CNS are hundreds of nanometers in width and height, but only few nanometers in thickness, sometimes as thin as a single-atomic-layer. Raman spectra of CNS featured D peaks and G peaks for sp@super 2@ bonded carbon, and low energy peaks, similar to RBM mode of single wall carbon nanotubes, were also observed. Analysis indicated that CNS is pure carbon without detectable contamination. BET measurement revealed a specific surface area of ~1300m@super 2@/g, which is the theoretical maximum value for a 2-layered graphene sheet. The high surface area makes CNS a potential candidate of catalyst support and hydrogen storage in fuel cell applications. Diode I-V curves, acquired to study the field emission property of nanosheets, showed a turn-on field as low as 1 V/µm and a current density of 2.2mA/mm@super 2@ over an area of 1mm@super 2@. This indicates that CNS is a good cathode material for cold field emission devices.