Graphene quantum dots embedded in Bi₂Te₃ nanosheets to enhance thermoelectric performance

Novel Bi₂Te₃/graphene quantum dots (Bi₂Te₃/GQDs) hybrid nanosheets with a unique structure that GQDs are homogeneously embedded in the Bi₂Te₃ nanosheet matrix have been synthesized by a simple solution-based synthesis strategy. A significantly reduced thermal conductivity and enhanced powder factor are observed in the Bi₂Te₃/GQDs hybrid nanosheets, which is ascribed to the optimized thermoelectric transport properties of the Bi₂Te₃/GQDs interface. Furthermore, by varying the size of the GQDs, the thermoelectric performance of Bi₂Te₃/GQDs hybrid nanostructures could be further enhanced, which could be attributed to the optimization of the density and dispersion manner of the GQDs in the Bi₂Te₃ matrix. A maximum ZT of 0.55 is obtained at 425 K for the Bi₂Te₃/GQDs-20 nm, which is higher than that of Bi₂Te₃ without hybrid nanostrucure. This work provides insights for the structural design and synthesis of Bi₂Te₃-based hybrid thermoelectric materials, which will be important for future development of broadly functional material systems.