Facile in situ solution synthesis of SnSe/rGO nanocomposites with enhanced thermoelectric performance

Abstract

Constructing nanostructured composite architectures has been considered as an effective strategy to reduce the lattice thermal conductivity (κ_L) and enhance the dimensionless figure of merit (ZT) of thermoelectric materials. Herein, a series of SnSe/reduced graphene oxide (rGO)-x (x = 0.1, 0.3, 0.5, 0.7 wt%) nanocomposites are controllably synthesised in situ via a facile single-step bottom-up solution method, where rGO nanosheets are incorporated intimately into the SnSe matrix. Nanocompositing performs two key functions: (i) significantly reducing the lattice thermal conductivity of the material, which can be attributed to enhanced phonon scattering from high-density SnSe/rGO interfaces, and (ii) improving the electrical conductivity over the low temperature range, as result of an increased carrier concentration. The subsequent thermoelectric performance of SnSe/rGO sintered pellets has been optimised by tuning the rGO mass fraction, with SnSe/rGO-0.3 achieving κ_L = 0.36 W m⁻¹ K⁻¹ at 773 K (cutting the κ_L of SnSe by 33%) to yield a maximum ZT of 0.91 at 823 K (representing a ∼47% increase compared to SnSe). This study provides a new pathway to improve the thermoelectric performance of polycrystalline SnSe by way of engineering metal chalcogenide/rGO composite architectures at the nanoscale.