High-Yield Synthesis, Controllable Evolution, 
and Thermoelectric Properties of Te/Bi2Te3 
Heterostructure Nanostrings
Te/Bi2Te3 heterostructure nanostrings composed of multiple hexagon Bi2Te3 nanosheets, which were strung together by Te nanowires, were rationally designed and synthesized via an in situ growth process. High-yield heterostructure products were obtained via the two-step solution phase method. The rhombohedral Bi2Te3 nanosheets and hexagonal phase Te nanowires were characterized using x-ray diffractometer patterns and high-resolution transmission electron microscopy images. Detailed scanning electron microscopy and transmission electron microscopy images revealed that the lengths of the nanostrings were approximately 3.6 μm, and the diameters of the Bi2Te3 nanosheets were approximately 290 nm. The results indicated that the dimensions and morphologies of the Te/Bi2Te3 heterostructure nanostrings can be controlled by regulating the dosage of Bi(NO3)3·5H2O from 0 mmol to 3 mmol, and the number of the Bi2Te3 nanosheets can be adjusted by controlling the concentration of N2H4·H2O. Exceedingly low thermal conductivities from 0.45 W m−1 K−1 to 0.49 W m−1 K−1 were demonstrated by the measurements of the thermoelectric properties at near-room temperature from 350 K to 500 K. The phonon scattering mechanisms were systematically analyzed using three-dimensional schematic structure models.