MODIFICATION OF PYROLYTIC-GRAPHITE SURFACE WITH PLASMA IRRADIATION

The effects of oxygen plasma treatment on the basal and edge surfaces of pyrolytic graphite have been investigated and compared with those of electrochemical treatment on their surfaces. The structural changes caused by the plasma and electrochemical treatments have been characterized by laser Raman and X-ray photoelectron spectroscopies. For the basal surface the plasma treatment causes the slight destruction of the graphitic structure, whereas for the edge surface it causes no marked destruction of the graphitic structure unlike the electrochemical treatment. The amount of surface oxygen both on the basal and edge surfaces increases after the plasma treatment. In particular, for the edge surface, a high surface oxygen concentration can be attained in a short treatment time. In addition, carbonyl-type groups appear to dominate in the plasma-treated basal and edge surfaces over -O- type groups. It can be concluded that oxidation by the plasma treatment is restricted to the vicinities of the surfaces and does not proceed to the internal structure of graphite, unlike the electrochemical treatment.