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

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 (sigma), Seebeck coefficient (S) and power factor (S-2 sigma) of the as-prepared Ag2Te nanostructures were measured and were found to be strongly dependent on the morphology of Ag2Te nanostructures. The S and sigma of Ag2Te hollow microspheres were higher than those of Ag2Te dendritic nanostructures, and S-2 sigma of Ag2Te hollow microspheres (9.01 x 10(-4) W m(-1) K-2) was 5 times that of dendritic nanostructures (1.80 x 10(-4) W m(-1) K-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.