In-Situ Chemical Thinning and Surface Doping of Layered Bi 2 Se 3 .

As a promising topological insulator, two-dimensional (2D) bismuth selenide (Bi 2 Se 3 ) attracts extensive research interest. Controllable surface doping of layered Bi 2 Se 3 becomes a crucial issue for the relevant applications. Here, we propose an efficient method for the chemical thinning and surface doping of layered Bi 2 Se 3 , forming Se/Bi 2 Se 3 heterostructures with tunable thickness ranging from a few nanometers to hundreds of nanometers. The thickness can be regulated by varying the reaction time and large-size few-layer Bi 2 Se 3 sheets can be obtained. Different from previous liquid-exfoliation methods that require complex reaction process, in-situ and thickness-controllable exfoliation of large-size layered Bi 2 Se 3 can be realized via the developed method. Additionally, the formation of Se nanomeshes coated on the Bi 2 Se 3 sheets remarkably enhance the intensity of Raman vibration peaks, indicating that this method can be used for surface-enhanced Raman scattering. The proposed chemical thinning and surface-doping method is expected to be extended to other bulk-layered materials for high-efficient preparation of 2D heterostructures.