Phases of graphene monoxide: Two-dimensional crystal forms of solid carbon monoxide

Graphene monoxide (GmO) – a 2-dimensional crystal form of solid carbon monoxide – has been demonstrated as a promising candidate for the Li-ion battery anode material due to properties of its first discovered structure, named α-GmO. In this work, new phases of GmO are predicted with density functional theory computations, in addition to previously experimentally discovered and theoretically modeled α- and β-GmO phases. Structure parameters, electronic and mechanical properties of the reported phases are investigated and compared. It is suggested that all phases of GmO can co-exist due to small formation energy differences. Hence a synthesis process of the pure material containing only one phase of GmO can be experimentally challenging. The models belong to different space groups and have different band structures, with some being insulators, semiconductors, or conductors. From analysis of the elastic moduli, it is concluded that GmO structures are softer than graphene and are likely to change their lattice parameters if they are present in a nanocomposite with graphene.