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.