▎ 摘　　要

Two-dimensional materials are in the forefront of material research due to their attractive electronic properties that can be employed for a wide range of applications. In last decades from the discovery of graphene, there has been a huge interest in the development of novel 2D materials such as metal oxides, transition-metal dichalcogenides and phosphides to name a few. Single element 2D materials such as the two-dimensional allotropes of the 14th group elements (silicene, germanene and stanene) and more recently the counterparts of the 15th group (phosphorene, arsenene, antimonene and bismuthene) and 13th group (borophene) have received considerable attention because of the intrinsically opened bandgap. Here, we cover the recent state of the art in the field of monoelemental 2D materials preparation using "bottom-up" approach together with discussion of possible future directions in material preparation. The review cover also the properties and some theoretical aspects of synthesis. (C) 2019 Elsevier Ltd. All rights reserved.