Kinetics of the reaction between steam and the basal plane of graphite

The gold decoration/transmission electron microscopy technique has been used to measure the rate of removal of carbon atoms from the basal plane of gra processes have been determined: removal of edge atoms surrounding the monolayer etch pits, and abstraction of carbon atoms within the basal plane which for edge carbon removal ranges from 0.02 at 600°C to 26 atom/atom active site/s at 900°C. The activation energy of 52 kcal/mole is close to the val of the saturated basal atoms (with 3 sp² bonds) may be expressed in terms of the probabilities of successful collisions of O atoms which are fo for both CO₂ and CH₂O reactions, are of the order of 10^-10 in the above temperature range. Comparison of the two reaction oxygen and water is the species responsible for basal atom abstraction. The gasification of graphite by steam is immensely anisotropic. At 23 torr H₂O the turnover frequency in the prismatic or edge directions, {1010} and {1120} faces, is higher than that on the basal {0001} plane by a factor of 4 × 10¹⁰ at 900°C and 4 × 10¹² at 700°C.