Kinetic study of graphite oxidation along two lattice directions

A systematic kinetic study of the oxidative etching of graphite basal planes along the a and c directions at temperatures up to 950 degrees C was undertaken. It was found that at temperatures above 875 degrees C, oxidation of graphite surfaces is initiated from basal plane carbon atoms as well as from point defects. This oxidation process gives rise to monolayer-depth pits with round shapes, as observed by scanning tunneling microscopy. The distribution of the diameters of the pits formed at high temperatures was broad. At lower temperatures, however, where pit formation is initiated solely at point defects, a narrow pit diameter distribution was observed. By analyzing the etching rates as a function of oxidation temperature, kinetic parameters such as etch rates and activation energies for the oxidation reactions along the a and c crystallographic directions of the graphite lattice were obtained. (c) 2005 Elsevier Ltd. All rights reserved.