Ultralow thermal conductivity and high thermoelectric performance of Cu2Se/TiO2 nanocomposite

In this work, nano-TiO2 particles were introduced into Cu2Se for enhancing thermoelectric (TE) properties. We found that nano-TiO2 can efficaciously decrease the thermal conductivity by increasing the phonon scattering, making it possible to enhance TE performance of Cu2Se to some extent. The minimum κ value was 0.35 W m−1 K−1, and the κL value was as low as 0.23 W m−1 K−1 for the Cu2Se/TiO2 nanocomposites. Further, a high ZT value of ∼1.6 at 1073 K and an average ZT (400 K–1073 K) value of ∼1 were obtained for the Cu2Se/TiO2 nanocomposite (the molar ratio of Ti to Se is 0.1).