Stability and synthesis of 2D metals and alloys : a review

As a newcomer to the family of two-dimensional (2D) material, 2D metals and alloys have seen rapid development in recent years because of their unique physical and chemical properties. Unlike freestanding atomistically thin 2D materials, such as graphene, the synthesis of 2D metals and alloys has been focused on either atomistically thin films under nanoscale geometric confinements or freestanding ultrathin films with a thickness ranging from a few to tens of nanometers. In this article, we will first review the recent theoretical works that aimed to understand the thermodynamic stability of 2D metals with or without geometrical confinements. After that, we will focus on the variety of methods that were developed to synthesize 2D metals and/or alloys. Finally, we will briefly discuss some state-of-the-art applications of 2D metals in bioimaging, photothermal therapy, sensing, nanodevices, and catalysis.