Low-dimensional heterostructures of tin nanoparticle-decorated Bi2Te3 nanoplates for reducing lattice thermal conductivity

Abstract

Low-dimensional materials such as nanoplates exhibit unique properties. Among them, thermoelectric materials are one of the most beneficial because they allow the application of a low-dimensional effect to reduce the lattice thermal conductivity. In this study, low-dimensional heterostructures of nanoparticle-decorated nanoplates were prepared to further reduce lattice thermal conductivity. Single-crystalline bismuth telluride (Bi2Te3) nanoplates with regular hexagonal shapes were fabricated by solvothermal synthesis. Subsequently, tin nanoparticles were decorated on the surface of the Bi2Te3 nanoplates via electroless plating with various concentrations of Sn precursor (SnCl2). Surface morphology and composition analyses indicated the presence of Sn on the nanoplate surface. To evaluate the original thermal properties of the nanoplates and not those of the fused nanoplates, polycrystalline film-formed nanoplates were prepared by pressing at 300 K under a pressure of 0.45 GPa. The in-plane lattice thermal conductivity of the tin nanoparticle-decorated nanoplates decreased with increasing SnCl2 concentration. At a SnCl2 concentration of 90 mM, the lattice thermal conductivity is 1.3 W/(m·K), which is approximately 30 % lower than that of the nanoplates without electroless plating. This indicates that the deposition of tin on the nanoplate surface reduces the phonon flow owing to phonon scattering. These findings provide a reference for controlling thermal properties of low-dimensional heterostructured materials.