Exfoliated MoS2 anchored on graphene oxide nanosheets for enhancing thermoelectric properties of single-walled carbon nanotubes

Abstract

Carbon nanotubes-based thermoelectric materials with high electrical conductivity (σ) and excellent mechanical properties have promising applications in flexible wearable devices. Two-dimensional transition metal sulfide MoS₂ has been used to enhance the thermoelectric properties of carbon nanotubes due to its high Seebeck coefficient (S). However, MoS₂ nanosheets are prone to agglomeration due to their high specific surface area, which causes lower doping efficiency. In this work, MoS₂@GO hybrids are successfully fabricated using a hydrothermal in-situ growth method to anchor exfoliated MoS₂ on graphene oxide (GO) nanosheets, and MoS₂@GO hybrids significantly enhance the interfacial interaction between MoS₂ and single-walled carbon nanotubes (SWCNT), improve the carrier mobility, lead to a simultaneous enhancement of the S and the σ. The maximum S value of MoS₂@GO/SWCNT is 42.3 ± 0.2 μV K⁻¹, the σ is 1173.2 ± 45.6 S cm⁻¹, and an optimum power factor (PF) of 208.8 ± 8.5 μW m⁻¹ K⁻² is obtained at room temperature, which reaches 261.3 ± 10.2 μW m⁻¹ K⁻² at 385 K. For application demonstration, a thermoelectric device is assembled by connecting six pairs of p-type MoS₂@GO/SWCNT and n-type copper sheets in series, which demonstrates an open-circuit voltage of 17.4 mV and an output power of 2.1 μW under a temperature difference of 50 K. Therefore, this study enriches the design and synthesis strategy of exfoliated MoS₂ and provides a new approach for the development of high-performance SWCNT-based thermoelectric materials, which has important potential applications in the field of wearable electronics.