Flexible 3D Porous MoS 2 /CNTs Architectures with ZT of 0.17 at Room Temperature for Wearable Thermoelectric Applications

Developing materials that possess high electrical conductivities (σ) and Seebeck coefficients ( S ), low thermal conductivities (κ), and excellent mechanical properties is important to realize practical thermoelectric (TE) devices. Here, 3D hierarchical architectures consisting of hybrid molybdenum disulfide (MoS 2 )/carbon nanotubes (CNTs) films are fabricated with the goal of increasing σ and decreasing κ. In these films, perpendicularly orientated CNTs interpenetrate restacked MoS 2 layers to form a 3D architecture, which increases the specific surface area and charge concentration. The MoS 2 /20 wt% CNTs film shows high σ (235 ± 5 S∙cm −1 ), high S (68 ± 2 µV∙K −1 ), and low κ (19 ± 2 mW∙m −1 ∙K −1 ). The corresponding figure of merit ( ZT ) reaches 0.17 at room temperature, which is 65 times higher than that of pure MoS 2 film. In addition, the MoS 2 /20 wt% CNTs film shows a tensile stress of 38.9 MPa, which is an order of magnitude higher than that of a control MoS 2 film. Using the MoS 2 /CNTs film as an active material and human body as a heat source, a flexible, wearable TE wristband is fabricated by weaving seven strips of the 3D porous MoS 2 /CNTs film. The wristband achieves an output voltage of 2.9 mV and corresponding power output of 0.22 µW at a temperature gradient of about 5 K.