Ultralow Thermal Conductivity and Large Figure of Merit in Low-Cost and Nontoxic Core-Shell Cu@Cu2O Nanocomposites

TL;DR

This paper reports on low-cost, nontoxic Cu@Cu2O nanocomposites with ultralow thermal conductivity and promising thermoelectric performance, achieved through a simple solution-phase synthesis, highlighting their potential for thermoelectric applications.

Contribution

First demonstration of thermoelectric properties of Cu@Cu2O nanocomposites synthesized via a facile solution method, showing superior thermoelectric figure of merit compared to many existing materials.

Findings

Ultralow thermal conductivity (~10^-3 of copper)

Large thermopower (~0.373 mV/K)

ZT of 0.16 at 320 K

Abstract

Identification of novel materials with enhanced thermoelectric (TE) performance is critical for advancing TE research. In this direction, this is the first report on TE properties of low-cost, nontoxic, and abundant core-shell Cu@Cu2O nanocomposites (NCs) synthesized using a facile and cheap solution-phase method. They show ultralow thermal conductivity of nearly 10-3 of copper bulk value, large thermopower ~0.373 mVK-1, and consequently, a TE figure of merit (ZT) of 0.16 at 320 K which is larger than those of many of the potential TE materials such as PbTe, SnSe and SiGe, showing its potential for TE applications. The ultralow thermal conductivity is mainly attributed to the multiscale phonon scattering from intrinsic defects in Cu2O, grain boundaries (GBs), lattice-mismatched interface as well as dissimilar vibrational properties. The large thermopower is associated with sharp modulation in carrier density of states (DOS) due to charge transfer between Cu and Cu2O nanoparticles (NPs), and carrier energy filtering.