Templating synthesis of uniform Bi2Te3 nanowires with high aspect ratio in triethylene glycol (TEG) and their thermoelectric performance

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.