Thermoelectric Bi2Te3 nanotubes synthesized by low-temperature aqueous chemical method

Bismuth telluride (Bi2Te3) nanotubes have been synthesized by a low-temperature aqueous chemical method, using Te powders and BiCl3 as the reactants, NaBH4 as the reductant and NaOH as the pH-controller. Microstructure investigations of powders show that the Bi2Te3 nanotubes have an average diameter of about 100 nm, with the length varying from about 500 nm to 1 μm. The tube walls have a thickness of about 30–40 nm. The growth mechanism of Bi2Te3 nanotubes is discussed in this paper. It is suggested that Bi2Te3 crystals initially grow as flat sheets, and then form a three-dimensional closed shell with the lowest surface energy. The shell must be curved, which could outcome to a Bi2Te3 nanotube at last.