Enhancement of thermoelectric figure of merit for Bi _0.5Sb _1.5Te ₃ by metal nanoparticle decoration

Introducing nanoinclusions in thermoelectric (TE) materials is expected to lower the lattice thermal conductivity by intensifying the phonon scattering effect, thus enhancing their TE figure of merit ZT. We report a novel method of fabricating Bi _0.5Sb _1.5Te ₃ nanocomposite with nanoscale metal particles by using metal acetate precursor, which is low cost and facile to scale up for mass production. Ag and Cu particles of ∼40 nm were successfully near-monodispersed at grain boundaries of Bi _0.5Sb _1.5Te ₃ matrix. The well-dispersed metal nanoparticles reduce the lattice thermal conductivity extensively, while enhancing the power factor. Consequently, ZT was enhanced by more than 25% near room temperature and by more than 300% at 520 K compared with a Bi _0.5Sb _1.5Te ₃ reference sample. The peak ZT of 1.35 was achieved at 400 K for 0.1 wt.% Cu-decorated Bi _0.5Sb _1.5Te ₃.