Theoretical Studies of the Reactions between Hyperthermal O(3P) and Graphite: Holes and the Second Layer

Abstract

Theoretical direct dynamic calculations on the basis of density functional theory are used to investigate hyperthermal collisions between O(3P) and highly oriented pyrolytic graphite (HOPG). The simulations suggest the HOPG surface becomes functionalized with epoxide groups as in previous works. Also, incoming O atoms can react at the surface to form O2 by way of an Eley–Rideal mechanism when the surface exposed to colliding O atoms is already functionalized with epoxides. A second layer of pristine graphene, included in the model, absorbs collision energy and significantly reduces the rates of reactions that liberate carbon from the surface, compared to single-layer models. Semiquinone functional groups are thought to be common at graphitic sheet edges and holes and to be a major source of CO and CO2. We deploy a model to explore the behavior of semiquinones when exposed to hyperthermal oxygen atoms. These groups are found to lead to CO and to play a role in the formation of epoxide groups on the underla...