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 Sn_m Bi_2n Te_3n+m homologous series, by a simple solution based synthesis. Few-layer nanosheets exhibit ultralow lattice thermal conductivity (κ_lat ) of 0.3-0.5 W m^-1  K^-1 and semiconducting electron-transport properties with high carrier mobility.