Flexible 3D Porous MoS₂/CNTs Architectures with ZT of 0.17 at Room Temperature for Wearable Thermoelectric Applications

Abstract 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 (MoS₂)/carbon nanotubes (CNTs) films are fabricated with the goal of increasing σ and decreasing κ. In these films, perpendicularly orientated CNTs interpenetrate restacked MoS₂ layers to form a 3D architecture, which increases the specific surface area and charge concentration. The MoS₂/20 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 MoS₂ film. In addition, the MoS₂/20 wt% CNTs film shows a tensile stress of 38.9 MPa, which is an order of magnitude higher than that of a control MoS₂ film. Using the MoS₂/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 MoS₂/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.