A Facile Surfactant-Assisted Reflux Method for the Synthesis of Single-Crystalline Sb₂Te₃ Nanostructures with Enhanced Thermoelectric Performance

Antimony telluride (Sb₂Te₃) and its based alloys are of importance to p-type semiconductors for thermoelectric applications near room temperature. Herein, we report a simple, low-energy intensive, and scalable surfactant-assisted reflux method for the synthesis of Sb₂Te₃ nanoparticles in the solvent ethylene glycol (EG) at low temperatures (120-180°C). The formation mechanism of platelike Sb₂Te₃ nanoparticles is proposed. Also, it is found that the size, shape, and chemical composition of the products could be controlled by the introduction of organic surfactants (CTAB, PVP, etc.) or inorganic salts (EDTA-Na₂, NaOH, etc.). Additionally, the collected Sb₂Te₃ nanoparticles were further fabricated into nanostructured pellets using cold-compaction and annealing techniques. Low resistivity [(7.37-19.4) × 10^-6 m], moderate Seebeck coefficient (103-141 V K^-1), and high power factor (10-16 × 10^-4 W m^-1 K^-2) have been achieved in our Sb₂Te₃-nanostructured bulk materials. The relatively low thermal conductivity (1.32-1.55 W m^-1 K^-1) is attained in the nanobulk made of PVP-modified nanoparticles, and values of ZT in the range of 0.24-0.37 are realized at temperatures ranging from 50 to 200°C. Our researches set forth a new avenue in promoting practical applications of Sb₂Te₃-based thermoelectric power generation or cooling devices.