The role of substitutional boron in carbon oxidation

An experimental and theoretical study of carbon oxidation in the presence o f substitutionally doped boron has been carried out. The effects of boron l oading, reaction temperature and degree of burnoff were analyzed for a rang e of carbon materials. Both inhibiting and catalytic effects were observed. Several semiempirical molecular orbital modeling approaches were used in a n attempt to rationalize these intriguing experimental findings in terms of electronic effects in the graphene layer. In particular, a critical analys is of the key adjustable parameters was performed. The oxidation results we re discussed in terms of a balance between three potentially competing effe cts of substitutional boron: (a) reduced total electron density; (b) decrea sed contribution of delocalized pi electrons to the electron density of the remaining carbon atoms; and (c) sigma electron localization on carbon atom s due to the higher electronegativity of carbon with respect to boron. (C) 1998 Elsevier Science Ltd. All rights reserved.