The utilization of CoSb3-based thermoelectric materials is currently confined to aviation applications, primarily attributed to their elevated thermal conductivity (κ) values. The incorporation of a nanostructuring approach, coupled with the introduction of a secondary phase, has demonstrated efficacy in diminishing the thermal conductivity (κ) values of CoSb3 materials. Here, the CoSb3/reduced graphene oxide (CoSb3/rGO) composites are obtained by sintering the as-synthesized powders, which ultra-fast synthesized in situ via microwave solvothermal method, under the High-temperature and High-Pressure (HTHP) conditions. The influence of reduced graphene oxide (rGO) on the structural and thermoelectric characteristics of CoSb3 composites has been systematically explored. In this study, CoSb3 nanoparticles with an average size of ∼33 nm exhibit uniform distribution, being effectively anchored onto the 2D sheets of rGO. In this work, the lattice thermal conductivity of CoSb3/rGO composites decreased with the addition of rGO. Based on the Debye-Callaway model, we attribute this to the effective scattering of phonons by the interface formed between the CoSb3 nanocrystals and the lamellar rGO. As a result, the CoSb3/rGO composite, containing 2 wt% graphene, exhibits a significantly enhanced maximum thermoelectric figure of merit (ZT) value, reaching ∼0.325 at 700 K. This represents an impressive improvement of approximately 300 % compared to the ZT value of the graphene-free CoSb3 bulk counterpart, which is ∼0.106. This study demonstrates the microwave solvothermal synthesis and HTHP sintering are in favor for an efficient, economical, and controllable synthesis of CoSb3/rGO composites, which provides a novel strategy for securing better thermoelectric performance.
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