▎ 摘　　要

In the first part of this study, DFT optimization is used to characterize the structure of multivacancies created in a graphene sheet by removing between 2 and 7 carbon atoms. We show that the stability of these multivacancies is mainly due to the formation of pentagons on their edges, and that, as a consequence, vacancies with an even number of missing atoms are more stable than vacancies with odd number of missing atoms, in line with previous theoretical conclusions and with experimental observations. Then, Born-Oppenheimer Molecular Dynamics followed by DFT optimization is performed to study the reactivity of these multivacancies with respect to molecular oxygen and water adsorption. Our calculations confirm that the less stable vacancies are also the most reactive with respect to oxygen and water, and that the final product of the reaction may depend on the vacancy size. (C) 2012 Elsevier B.V. All rights reserved.