Stone-Wales Defect and Vacancy-Assisted Enhanced Atomic Orbital Interactions Between Graphene and Ambient Gases: A First-Principles Insight.

Abstract

Graphene has magnificent fundamental properties for its application in various fields. However, these fundamental properties have been observed to get perturbed by various agents like intrinsic defects and ambient gases. Degradation as well as p-type behavior of graphene under an ambient atmosphere are some of the properties that have not yet been explored extensively. In this work, interactions of different ambient gases, like N2, O2, Ar, CO2, and H2O, with pristine and defective graphene are studied using density functional theory (DFT) computations. It is observed that while the pristine graphene is chemically and physically inert with ambient gases, except for oxygen, its interaction with these ambient gases increases significantly in the presence of carbon vacancies and Stone–Wales (SW) defects. We report that Ar and N2 are apparently not inert with defective graphene, as they also influence its fundamental properties like band structure, mid gap (trap) states, and Fermi energy level. We have also found that while oxygen makes pristine graphene p-type, the phenomenon amplifies in the presence of SW defects. Besides, in the presence of carbon vacancies, N2, H2O, and CO2 also make the graphene monolayer p-type. Among ambient gases, oxygen is the real performance and reliability killer for graphene. Its reaction is seeded by a carbon vacancy, which initiates its degradation by local formation of graphene oxide.