Bismuth’s small effective mass (∼0.001m0) and large mean
free path (∼0.4 mm at 4 K) make Bi nanotube an interesting
system for studying quantum confinement effects.11 In addition,
nanoscaled bismuth materials have recently been suggested to
have enhanced thermoelectric properties at room temperature.12
However, owing to the relatively low melting point of Bi (271.3
°C), the synthesis of Bi nanotubes is much more difficult than
that for carbon or MX2 analogies. Most of the existing hightemperature
approaches, such as arc-discharge evaporation, laser
ablation, or chemical vapor deposition are inappropriate for
synthesis of Bi nanotubes. Hence, the investigations of rational
synthesis, physical properties, and applications of the Bi nanotubes
or nanowires remain as challenges to materials scientists.
We have developed a low-temperature controlled hydrothermal
reduction method13 to prepare Bi nanotubes. The chemical reaction
we employed for synthesis of the Bi nanotubes can be formulated