A Facile Surfactant-Assisted Reflux Method for the Synthesis of Single-Crystalline Sb<sub>2</sub>Te<sub>3</sub> Nanostructures with Enhanced Thermoelectric Performance

Antimony telluride (Sb<sub>2</sub>Te<sub>3</sub>) 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 Sb<sub>2</sub>Te<sub>3</sub> nanoparticles in the solvent ethylene glycol (EG) at low temperatures (120–180 °C). The formation mechanism of platelike Sb<sub>2</sub>Te<sub>3</sub> 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-Na<sub>2</sub>, NaOH, etc.). Additionally, the collected Sb<sub>2</sub>Te<sub>3</sub> nanoparticles were further fabricated into nanostructured pellets using cold-compaction and annealing techniques. Low resistivity [(7.37–19.4) × 10<sup>–6</sup> Ω m], moderate Seebeck coefficient (103–141 μV K<sup>–1</sup>), and high power factor (10–16 × 10<sup>–4</sup> W m<sup>–1</sup> K<sup>–2</sup>) have been achieved in our Sb<sub>2</sub>Te<sub>3</sub>-nanostructured bulk materials. The relatively low thermal conductivity (1.32–1.55 W m<sup>–1</sup> K<sup>–1</sup>) is attained in the nanobulk made of PVP-modified nanoparticles, and values of <i>ZT</i> 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 Sb<sub>2</sub>Te<sub>3</sub>-based thermoelectric power generation or cooling devices.