Hierarchical Bi₂ Te₃ Nanostrings: Green Synthesis and Their Thermoelectric Properties

Bi₂ Te₃ hierarchical nanostrings have been synthesized through a solvothermal approach with the assistance of sucrose. The hierarchical Bi₂ Te₃ was supposed to be fabricated through a self-assembly process. Te nanorods first emerge with the reduction of TeO₃^2- followed by heterogeneous nucleation of Bi₂ Te₃ nanoplates on the surface and tips of Te nanorods. Te nanorods further transform into Bi₂ Te₃ nanorods simultaneously with the nanoplates' growth leading to a hierarchical structure. By controlling the reaction kinetics by adding different amount of ethylene glycol, the length of nanorods and the number of nanoplates could be tailored. The use of sucrose is vital to the formation of hierarchical structure because it not only serves as a template for the well-defined growth of Te nanorods but also promotes the heterogeneous nucleation of Bi₂ Te₃ in the self-assembly process. The Bi₂ Te₃ nanomaterial shows a moderate thermoelectric performance because of its hierarchical structure. This study shows a promising way to synthesize Bi₂ Te₃ -based nanostructures through environmental friendly approach.