Significant improvement of thermoelectric performance in nanostructured bismuth networks

We present here the first experimental evidence of a significant enhancement in the thermoelectric properties of networks containing bismuth nanotubes and nanowires fabricated via aqueous chemical routes. The as-prepared samples revealed two dominant morphologies: double wall nanotubes with 4–6 nm diameter and nanowires of 15–30 nm diameters. Transport measurements in the range 15–300 K were performed on cold pressed pellets which contained these bismuth nanostructures. We find that the cold pressed networks of nanostructured bismuth exhibit a non-metallic behavior, the corresponding room temperature resistivities vary from ∼0.54 to 5.8 mΩ-cm, depending on the detailed nanomorphology. The measured thermal conductivity for the networks of bismuth nanotubes and nanowires is almost 5 times lower compared to bismuth powder at room temperature. The observed improvement in the thermoelectric performance has been attributed to the reduced lattice thermal conductivity of nanostructured bismuth networks via interface scattering.

Graphical AbstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Synthesis of double wall Bi nanotubes and Bi nanowires using facile aqueous chemical routes. ► Lowest room temperature electrical resistivity is obtained for Bi nanotubes. ► We present the first experimental study of thermoelectric properties of arrays of Bi nanotubes. ► A five-fold decrease in the thermal conductivity of Bi nanostructured networks is reported.