Graphitic carbon nitride-bismuth antimony telluride nanocomposites: A potential material for thermoelectric applications

Abstract

Modified forms of Bi2Te3 system attracts immense importance in thermoelectric generation by providing a green and clean technology for converting low-grade waste heat into electrical energy. Herein, we have explored the potential of a new material graphitic carbon nitride (g-C3N4) for tuning the thermoelectric properties of Bi0·4Sb1·6Te3. The electronic and lattice transport properties of Bi0·4Sb1·6Te3 are effectively decoupled through nanostructuring, modification of carrier concentration through defect engineering and embedding g-C3N4 nanostructures in the bulk material which leads to the synergetic optimization of power factor and suppressed thermal conductivity due to all-scale hierarchical architecture. All the Bi0·4Sb1·6Te3/g-C3N4 nanocomposites exhibit reduction in thermal conductivity and we obtained an ultra-low thermal conductivity of 0.33 W/mK for Bi0·4Sb1·6Te3 nanocomposite with 1% g-C3N4. The simultaneous optimization of electrical and lattice transport properties leads to a marked improvement in figure of merit from 0.295 for pristine Bi0·4Sb1·6Te3 to a peak value of 1.09 for Bi0·4Sb1·6Te3 with 0.50% g-C3N4.