Defects in two-dimensional elemental materials beyond graphene

Two-dimensional (2D) elemental materials of group-IIIA, -IVA, -VA -VIA and IVB, beyond graphene, one sheet of carbon atoms with honeycomb structural arrangement, such as borophene, gallenene, silicene, germanene, phosphorene, stanene, arsenene, antimonene, bismuthene, selinene, tellurene, and hafnene, have received enormous increasing scientific interest owing to either their exclusive fundamental physical-chemical properties and/or potential applications in nanotechnology. Defects are present in 2D materials as in any other material, affecting their structural, mechanical, magnetic, and electronic properties. Here, we deal with recent theoretical and experimental insights on the discovery of new 2D elemental materials beyond graphene, in addition to the presence of different types of structural point defects, including Stone-Wales, single vacancy and bivacancies, as well as line defects or grain boundaries, and adatoms. Importantly, defects in 2D materials, as in all materials, can negatively affect their physical properties or, if properly controlled, be considered as promoters of novel unexpected, tailored quantum phenomena.