Rational Design of Bi₂Te₃ Polycrystalline Whiskers for Thermoelectric Applications

Bi2Te3 polycrystalline whiskers consisting of interconnected nanoplates have been synthesized through chemical transformation from In2Te3 polycrystalline whisker templates assembled by nanoparticles. The synthesized Bi2Te3 whiskers preserve the original one-dimensional morphology of the In2Te3, while the In2Te3 nanoparticles can be transformed into the Bi2Te3 thin nanoplates, accompanied by the formation of high-density interfaces between nanoplates. The hot-pressed nanostructures consolidated from Bi2Te3 polycrystalline whiskers at 400 °C demonstrate a promising figure of merit (ZT) of 0.71 at 400 K, which can be attributed to their low thermal conductivity and relatively high electrical conductivity. The small nanoparticles inherited from the polycrystalline whiskers and high-density nanoparticle interfaces in the hot-pressed nanostructures contribute to the significant reduction of thermal conductivity. This study provides a rational chemical transformation approach to design and synthesize polycrystalline microstructures for enhanced thermoelectric performances.