Size-Controlled Au–Cu₂Se Core–Shell Nanoparticles and Their Thermoelectric Properties

Abstract

One promising approach to improving thermoelectric energy conversion is to use nanostructured interfaces that enhance Seebeck coefficient while reducing thermal conductivity. Here, we synthesized Au–Cu2Se core–shell nanoparticles with different shell thicknesses by controlling the precursor concentration in solution. The Au–Cu2Se core–shell nanoparticles are about 37–53 nm in size, and the cores of the nanostructures are composed of Au nanoparticles with sizes of ∼11 nm. The effect of shell thickness on the thermoelectric properties of core–shell nanocomposites is investigated after sintering the core–shell nanoparticles into pellets using the spark plasma sintering (SPS) technique. The power factor was optimized by the synergetic effect of the improvement of Seebeck coefficient by energy filtering in the Au/Cu2Se interface and the effective tuning of carrier concentration by Ohmic contact in the interface. The lattice thermal conductivity of core–shell nanocomposites is reduced by coherent phonon scattering, which is caused by the wavelike interference of phonons due to the phase shift in the core–shell interface. The highest ZT value of 0.61 is obtained at 723 K for Au–Cu2Se core–shell nanocomposite with a shell thickness of 21 nm, which is higher than that of pure Cu2Se nanocomposite or a mixture of Au and Cu2Se particles.

Roles of Heterojunction and Cu Vacancies in the Au@Cu2–xSe for the Enhancement of Electrochemical Nitrogen Reduction Performance

“…As a result, the electronic properties of both Au and Cu 2– x Se are altered, leading to a decrease in electron density within the Cu 2– x Se shell due to the Ohmic junctions . The electron-deficient Cu 2– x Se shell is believed to achieve enhanced ENRR activity by facilitating N 2 adsorption and activation, which is more favorable compared to the interaction of H + with the electrocatalyst. ,, Consequently, the parasitic H 2 formation is restricted, while the desirable formation of NH 3 is enhanced in the ENRR system with aqueous 0.1 M KOH.…”

Core–shell nanostructures for better thermoelectrics

“…110 Similarly, enhanced Seebeck coefficient with reduced thermal conductivity was observed in Au@Cu 2 Se core-shell nanoparticles. 111 Jin et al synthesized these nanoparticles with different shell thicknesses through the hydrothermal route by controlling the precursor concentration. 111 With the improvements in the Seebeck coefficient by energy filtering in the core-shell interface and reduced lattice thermal conductivity of core-shell due to coherent phonon scattering, a high zT value of 0.61 was obtained at 723 K in Au@Cu 2 Se core-shell nanoparticles with a shell thickness of 21 nm.…”

“…111 Jin et al synthesized these nanoparticles with different shell thicknesses through the hydrothermal route by controlling the precursor concentration. 111 With the improvements in the Seebeck coefficient by energy filtering in the core-shell interface and reduced lattice thermal conductivity of core-shell due to coherent phonon scattering, a high zT value of 0.61 was obtained at 723 K in Au@Cu 2 Se core-shell nanoparticles with a shell thickness of 21 nm. The zT achieved from the core-shell structures is higher than that of the composite mixture of Au and Cu 2 Se particles or pure Cu 2 Se (Fig.…”

Current State‐of‐the‐Art in the Interface/Surface Modification of Thermoelectric Materials

“…Increasing the amount of Cu and Se precursors added to a fixed amount of Au nanoparticles causes the shell thickness to accordingly increase, thereby leading to a decreased thermal conductivity and increased zT value. [ 280 ]…”

“…The filled square symbols indicate the carrier concentration of the Au/Cu 2 Se mixture. [ 280 ] Reproduced with permission. [ 280 ] Copyright 2020, American Chemical Society.…”