Enhanced Thermoelectric Performance of Novel Reaction Condition-Induced Bi<sub>2</sub>S<sub>3</sub>-Bi Nanocomposites
Tarachand Tarachand, Gunadhor Singh Okram, Binoy Krishna De, Siddhartha Dam, Shamima Hussain, Vasant Sathe, Uday Deshpande, Archana Lakhani, Y. K. Kuo
Abstract
This is the first report on the enhanced thermoelectric (TE) properties of novel reaction-temperature ( T Re ) and duration-induced Bi 2 S 3 -Bi nanocomposites synthesized using a facile one-step polyol method. They are well characterized as nanorod composites of orthorhombic Bi 2 S 3 and rhombohedral Bi phases in which the latter coats the former forming Bi 2 S 3 -Bi core–shell-like structures along with independent Bi nanoparticles. A very significant observation is the systematic reduction in electrical resistivity ρ with a whopping 7 orders of magnitude (∼10 7 ) with just reaction temperature and duration increase, revealing a promising approach for the reduction of ρ of this highly resistive chalcogenide and hence resolving the earlier obstacles for its thermoelectric application potentials in the past few decades. Most astonishingly, a TE power factor at 300 K of the highest Bi content nanocomposite pellet, made at 27 °C using ∼900 MPa pressure, is 3 orders of magnitude greater than that of hot-pressed Bi 2 S 3 . Its highest ZT at 325 K of 0.006 is over twice of that of similarly prepared CuS or Ag 2 S-based nanocomposites. A significantly improved TE performance potential near 300 K is demonstrated for these toxic-free and rare-earth element-free TE nanocomposites, making the present synthesis method as a pioneering approach for developing enhanced thermoelectric properties of Bi 2 S 3 -based materials without extra sintering steps.