Templating synthesis of uniform Bi2Te3nanowires with high aspect ratio in triethylene glycol (TEG) and their thermoelectric performance

Abstract

Highly uniform Bi₂Te₃ nanowires with a length of tens of micrometres and a diameter of 15–17 nm can be synthesized through a simple and fast solution process by using ultrathin Te nanowires as sacrificial templates. Different from previous template-directed hydrothermal synthesis, here we used heating mantle as the reactor for preparing Bi₂Te₃ nanowires, which not only makes the reaction perform more efficiently and be finished within one hour, but also can achieve more uniform nanowires. As-synthesized Bi₂Te₃ nanowires have a hexagonal-phase single crystalline structure. It was found that using triethylene glycol (TEG) as solvent and precise controlling reaction temperature and time were crucial to obtain high-quality single crystal Bi₂Te₃ nanowires. The formation process of Bi₂Te₃ nanowires was believed to include both Kirkendall effect and Ostwald ripening, according to the experimental observations. Compared with other Bi₂Te₃ nanostructures and bulk Bi₂Te₃ materials, the thermal conductivity of Bi₂Te₃ nanowire pellet decreased evidently, verifying that one-dimensional thermoelectric nanomaterials indeed exhibit lower thermal conductivity.