Thermoelectric performance of hydrothermally synthesized micro/nano Cu2-xS

Among the state-of-the-art thermoelectric materials, copper sulfides (Cu2S) have been predicted as promising thermoelectric materials due to their low intrinsic thermal conductivity. However, they still confront the problems with lower electrical properties, which distinctly restrict their thermoelectric application. Significant enhancement of thermoelectric properties is a great challenge owing to the common interdependence of electrical and thermal conductivity. Herein, a micro/nano Cu2-xS composite, with significantly enhanced thermoelectric properties, is prepared via a simple hydrothermal method. Due to the synergistic effect of the introduced nanostructure and the increased Cu1.96S contents, the micro/nano Cu2-xS bulk samples present a power factor of 10.1 μW cm−1 K−2 at 773 K. Meanwhile, a decrease of the thermal conductivity to 0.69 W m−1 K−1 is obtained, originating from the strong phonon scattering of micro/nano structure. Remarkably, a ZTmax value of 1.1 at 773 K is obtained, which is higher than the reported Cu2-xS thermoelectric material using chemical methods. This study proposes a facile microstructure engineering strategy for the development of high-performance thermoelectric materials.