Enhanced thermoelectric properties of Au nanodot-included Bi₂Te₃ nanotube composites

Herein, we report on a scalable synthesis of Au nanodot (Au-ND)/Bi₂Te₃ nanotube (BT-NT) nanocomposites by the bottom-up synthesis of hybrid raw materials and subsequent spark plasma sintering, and their thermoelectric properties were systematically compared with those of Au-doped Bi₂Te₃ compounds. The Au nanodots were included as seeds and co-crystallized in the crystal growth of BT-NTs, which were well-dispersed in the Bi₂Te₃ matrix as nanoinclusions (10-20 nm). The thermoelectric performance (ZT) of the Au-ND/BT-NT nanocomposite was found to be enhanced by ∼67%, compared to pristine Bi₂Te₃ due to electron energy filtering and phonon scattering effects in the presence of embedded Au-NDs. The resulting compound showed an enhanced power factor (23.0 × 10^-4 W m^-1 K^-2 @ 440 K, 27% improvement) and a reduced lattice thermal conductivity (0.47 W m^-1 K^-1 @ 440 K, 22% reduction). The peak ZT value of the present compound (0.95 @ 480 K) is larger than that of n-type single crystalline Bi₂(Te,Se)₃, which is one of the highest among the reported values for n-type Bi₂Te₃-based materials synthesized using a soft chemical route.