Room-temperature solution synthesis of Ag2Te hollow microspheres and dendritic nanostructures, and morphology dependent thermoelectric properties

Abstract

Ag₂Te hollow microspheres and dendritic nanostructures were synthesized by a simple room-temperature solution method using AgNO₃, TeO₂, hydrazine hydrate and ethylenediamine. The as-prepared Ag₂Te hollow microspheres and dendritic nanostructures were formed by the self-assembly of nano-building blocks of nanoparticles and nanosheets, respectively. The chemical reaction and formation mechanism of Ag₂Te nanostructures were proposed. The products were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The electrical conductivity (σ), Seebeck coefficient (S) and power factor (S²σ) of the as-prepared Ag₂Te nanostructures were measured and were found to be strongly dependent on the morphology of Ag₂Te nanostructures. The S and σ of Ag₂Te hollow microspheres were higher than those of Ag₂Te dendritic nanostructures, and S²σ of Ag₂Te hollow microspheres (9.01 × 10⁻⁴ W m⁻¹K⁻²) was 5 times that of dendritic nanostructures (1.80 × 10⁻⁴ W m⁻¹K⁻²). The observed thermoelectric properties of Ag₂Te nanostructures may be due to the strong quantum confinement effect introduced by decreasing the dimensionality and size of nano-building blocks from dendritic nanostructures to hollow microspheres.