AVS 52nd International Symposium
    Surface Science Monday Sessions
       Session SS-MoP

Paper SS-MoP21
Investigation of sp@super 2@ Carbon in Nanodiamond

Monday, October 31, 2005, 5:00 pm, Room Exhibit Hall C&D

Session: Surface Science Poster Session
Presenter: J. Hu, University of Oxford, UK
Authors: J. Hu, University of Oxford, UK
J. Foord, University of Oxford, UK
Correspondent: Click to Email
Diamond electrodes have wide application in electroanalysis, electrolysis, waste water treatment etc. due to superior properties, such as chemical inertness, high overvoltage, and resist to electrode fouling. The sp@super 2@ carbon inclusion in microcrystalline and nanodiamond is believed to make a major contribution to the performance of diamond electrodes. We investigate this in the present paper. Microcrystalline and nanodiamond films are grown on Si (100) and polished Ti sheet with different methane concentrations by MWCVD. The samples are characterized by Raman Spectroscopy, SEM, XPS, Voltammetry and conductivity. With increasing concentration of methane from 1% to 4 %, the grain size decreases slightly and becomes more homogeneous. With further higher concentration of methane, the samples are nanocrystalline with typical grains of around 200 nm. XPS and EELS indicate that only a trace amount of sp@super 2@ carbon is present on sample surface. About 1% percent of sp@super 2@ carbon in microcrystalline diamond is etched away in electrochemical polarization at 2.2V in 1M HNO@sub 3@ solution, and more sp@super 2@ carbon can be etched away for nanodiamond. This shows that most of the sp@super 2@ carbon inclusions are present in grain boundaries instead of embedded into diamond grains or present as graphite grains at the electrode surface. Electrochemical etching protocols are examined, to minimize unwanted effect of sp@super 2@ carbon on the performance of diamond electrode.