Synthesis and phase-engineering of ultrathin two-dimensional nanomaterials

Ultrathin two-dimensional (2D) nanomaterials have attracted increasing attention thanks to their appealing properties and great potentials in a wide range of applications. In order to tune their properties and enhance their performance in various applications, tremendous efforts have been devoted to exploring different strategies for the synthesis and structural engineering of ultrathin 2D nanomaterials. In particular, considerable progress has been made in recent years on the phase engineering of these materials, i.e., the strategy of phase engineering of nanomaterials (PEN), to adjust their properties and functions. In this article, we summarize the recent progress on the preparation and phase engineering of ultrathin 2D nanomaterials, in which the explorations of ultrathin 2D transition metal dichalcogenides (TMDs), metals as well as amorphous and amorphous/crystalline 2D nanomaterials are emphasized. Finally, we propose the personal perspectives on challenges and opportunities in this promising field based on the current research.