Highly porous thermoelectric composites with high figure of merit and low thermal conductivity from solution-synthesized porous Bi2Si2Te6 nanosheets

Abstract

Layer-structured Bi₂Si₂Te₆ has garnered significant attention in the field of thermoelectrics due to its exceptional thermoelectric properties and unique structural characteristics. Enhancing the transport properties of composites by manipulating the thermal and electrical properties of materials through the fabrication of porous nanostructured materials has emerged as a promising strategy. This paper presents a study on enhancing the thermoelectric (TE) properties of Bi₂Si₂Te₆ nanosheets (BST NSs) through nanostructuring and the fabrication of porous BST NSs (p-BST). The process involves Li intercalation and exfoliation to obtain BST NSs, followed by the creation of p-BST composites by introducing nanosized pores onto the surface of the NSs using high-power sonification for various durations. The incorporation of the porous structure effectively increases phonon scattering, leading to a decrease in the lattice thermal conductivity (κ_l) of the composite. The p-BST(2) composite demonstrates significantly low κ and enhanced thermoelectric figure of merit (ZT) values (∼0.63 W m⁻¹ K⁻¹ and ∼0.083) at room temperature. These results highlight the efficacy of porous structure preparation as a promising strategy for enhancing the thermoelectric performance of chalcogenide-based composites, offering potential solutions to environmental degradation and energy shortages.