Preparation and thermoelectric properties of MoS2/Bi2Te3 nanocomposites

MoS2 nanosheets with size of several-hundred nanometers were prepared by a hydrothermal intercalation/exfoliation method, then MoS2/Bi2Te3 composite nanopowders were prepared by a microwave-assisted wet chemical method using the MoS2 nanosheets, TeO2, Bi(NO3)3·5H2O, KOH and ethylene glycol as raw materials. Bulk MoS2/Bi2Te3 nanocomposites were prepared by hot pressing the MoS2/Bi2Te3 composite nanopowders with MoS2 nanosheet content ranging from 0 to 17 wt% at 80 MPa and 648 K in vacuum. X-ray photoelectron spectroscopy and X-ray diffraction analyses indicate that MoS2 and Bi2Te3 did not react each other during the hot pressing. FESEM observation reveals that the MoS2/Bi2Te3 composite samples had a more compact microstructure than the pristine Bi2Te3 bulk sample. The MoS2 phase was relatively randomly dispersed in the composite. At a given temperature, the electrical conductivity of the composites increases first then decreases as the MoS2 content increases, whereas the Seebeck coefficient of the bulk nanocomposites does not change much. A highest power factor, ~18.3 μW cm−1 K−2 which is about 30% higher than that of pristine Bi2Te3 sample, at 319 K has been achieved from a nanocomposite sample containing 6 wt% MoS2.