Facile synthesis of Cu7Te4 nanorods and the enhanced thermoelectric properties of Cu7Te4–Bi0.4Sb1.6Te3 nanocomposites

Abstract Nanocomposite thermoelectric (TE) materials have received great interest in recent years due to the large improvement in the figure of merit (ZT), which exceed the ZT≈1 barrier. Herein, we report a facile method for the synthesis of surfactant-free Cu 7 Te 4 using Te nanorods as templates, and the observed improvement of TE properties obtained by dispersing Cu 7 Te 4 nanorods in a Bi 0.4 Sb 1.6 Te 3 matrix. The matrix itself yields a maximum power factor of 2.45 mW/m K 2 at 300 K, while the addition of 5 wt% of Cu 7 Te 4 nanorods increases and shifts the maximum power factor to 3.3 mW/m K 2 at 345 K. The maximum ZT obtained for the 5 wt% Cu 7 Te 4 –Bi 0.4 Sb 1.6 Te 3 nanocomposite is 1.14 at 444 K, which is nearly 27% higher than the peak ZT achieved for the Bi 0.4 Sb 1.6 Te 3 matrix.