▎ 摘　　要

The possible existence and properties of different polytypes of graphene monoxide (GmO)-two-dimensional crystalline monolayers composed of equal numbers of C and O atoms-are investigated using density functional calculations. Structural parameters, electronic, and mechanical properties of the different phases, including the previously reported alpha and beta phases, are determined and compared. It is suggested that multiple phases of GmO can coexist in the same composite, but developing a synthesis process for single-phase GmO may be experimentally challenging. The phases exhibit band structures ranging from insulating to metallic. From an analysis of the calculated elastic moduli, it is concluded that all the GmO structures are softer than graphene and are likely to change their lattice parameters if present in a composite with graphene.