Facile synthesis of hetero-structured Bi2S3/SnS2 composite and its improved thermoelectric properties

Abstract

In this study, bismuth sulfide/tin (IV) sulfide (Bi2S3/SnS2) heterostructure nanocomposites were fabricated to obtain high-performance thermoelectric composite materials. The Bi2S3/SnS2 composites were prepared via solution mixing using a two-step hydrothermal reactor. First, flower-like-shaped Bi2S3 was prepared, after which the as-synthesized Bi2S3 was decorated with SnS2 nanocomposites. The formation of a unique Bi2S3/SnS2 heterostructure was achieved through a thioacetamide-induced surfactant-assisted reaction process. The thermoelectric power factor of the Bi2S3/SnS2 composites was optimized by controlling their Bi:Sn ratios, and changes in the thermoelectric properties of the composites were investigated by examining the change in their carrier transport properties. The composite achieved a maximum thermoelectric power factor of ~99.7 μW/m·K2 at a Bi:Sn ratio of 1:0.2, which is ~5.1 times larger than that of pristine Bi2S3. This increase in the power factor was ascribed to the fact that the enhanced electrical conductivity outweighs the reduction effect of the Seebeck coefficient. The hetero-structured Bi2S3/SnS2 composite is a promising strategy for realizing high-performance sulfur-based thermoelectric composite materials.