Synthetic Nanosheets of Natural van der Waals Heterostructures.

Creation of new van der Waals heterostructures by stacking different two dimensional (2D) crystals on top of each other in a chosen sequence is the next challenge after the discovery of graphene, mono/few layer of h-BN, and transition-metal dichalcogenides. However, chemical syntheses of van der Waals heterostructures are rarer than the physical preparation techniques. Herein, we demonstrate the kinetic stabilization of 2D ultrathin heterostructure (ca. 1.13-2.35 nm thick) nanosheets of layered intergrowth SnBi2 Te4 , SnBi4 Te7 , and SnBi6 Te10 , which belong to the Snm Bi2n Te3n+m homologous series, by a simple solution based synthesis. Few-layer nanosheets exhibit ultralow lattice thermal conductivity (κlat ) of 0.3-0.5 W m-1  K-1 and semiconducting electron-transport properties with high carrier mobility.