Bi₂Te₃, the most superior thermoelectric material in the low and medium temperature regions, is now widely used in various thermoelectric devices. Despite the great progress in recent years, a simple and environmentally friendly method of nanosized Bi₂Te₃ materials with high thermoelectric properties is still a great challenge. In this paper, we explored an efficient and rapid synthesis of Bi₂Te₃ nanosheet materials based on the solvothermal method that is environmentally friendly. Bi₂Te₃ nanomaterials with good thermoelectric properties were synthesized by modulating the morphology of Bi₂Te₃ nanomaterials by changing the experimental conditions. Single-crystal hexagonal Bi₂Te₃ nanosheets with regular morphology, uniform size and good monodispersity were prepared by using (CH₂OH)₂ as the reaction solvent and weak reducing agent, and by controlling the reaction temperature, NaOH addition and reaction precursors during the synthesis process. The sintered sample has a large number of nanocrystalline boundaries, which can increase phonon scattering and reduce thermal conductivity. The results of the study show that the Bi₂Te₃ nanomaterials prepared in this paper have good thermoelectric properties with a thermoelectric figure of merit 14% higher than the commercial Bi₂Te₃. This work provides an efficient, rapid and environmentally friendly method for the preparation of Bi₂Te₃ nanomaterials and is a guideline for the subsequent research of Bi₂Te₃-based thermoelectric materials.

Bi2Te3 nanomaterials; solvothermal method; phonon scattering; thermal conductivity; thermoelectric figure of merit