The p-type Sb2Te3 alloy, a binary compound belonging to the V2VI3-based materials, has been widely used as a commercial material in the room-temperature zone. However, its low thermoelectric performance hinders its application in the low-medium temperature range. In this study, we prepared Sb2Te3 nanosheets coated with nanometer-sized Pt particles using a combination of solvothermal and photo-reduction methods. Our findings demonstrate that despite the adverse effects on certain properties, the addition of Pt particles to Sb2Te3 significantly improves the thermoelectric properties, primarily due to the enhanced electronic conductivity. The optimal ZT value reached 1.67 at 573 K for Sb2Te3 coated with 0.2 wt% Pt particles, and it remained above 1.0 within the temperature range of 333-573 K. These values represent a 47% and 49% increase, respectively, compared to the pure Sb2Te3 matrix. This enhancement in thermoelectric performance can be attributed to the presence of Pt metal particles, which effectively enhance carrier and phonon transport properties. Additionally, we conducted a Density Functional Theory (DFT) study to gain further insights into the underlying mechanisms. The results revealed that Sb2Te3 doped with Pt exhibited a doping level in the band structure, and a sharp rise in the Density of States (DOS) was observed. This sharp rise can be attributed to the presence of Pt atoms, which lead to enhanced electronic conductivity. In conclusion, our findings demonstrate that the incorporation of nanometer-sized Pt particles effectively improves the carrier and phonon transport properties of the Sb2Te3 alloy. This makes it a promising candidate for medium-temperature thermoelectric applications, as evidenced by the significant enhancement in thermoelectric performance achieved in this study.
Keywords: Pt nanoparticles; Sb2Te3 nanosheets; solvothermal method; thermoelectric materials.