Construction of a 3D-rGO network-wrapping architecture in a YbyCo4Sb12/rGO composite for enhancing the thermoelectric performance

Abstract

Nanostructures and nano-composites have been shown to be effective in depressing the lattice thermal conductivity and improving the performance of thermoelectric materials. However, ZT enhancement by nano-particle dispersion is limited only to a restricted level due to the difficulty in increasing the particle contents while maintaining a uniform and narrow size distribution. In the present work, Yb_yCo₄Sb₁₂-based nano-composites with reduced graphene oxide (rGO) layers of several nanometers intercalated on the grain boundary matrix forming a 3D network have been prepared through a simple in situ reduction approach using graphene oxide (GO) as the precursor. The 3D-rGO network wrapping architecture dramatically reduced the lattice thermal conductivity due to enhanced interparticle and intraparticle phonon scattering effects, and simultaneously enhanced the Seebeck coefficient due to the energy filtering effect of the grain boundary semiconductive rGO layer with nanometer thickness. The maximum ZT value of 1.51 was achieved for the Yb_0.27Co₄Sb₁₂/rGO (0.72 vol%) composite at 850 K, outperforming all single-filled skutterudites and their nanocomposites ever reported.