Bi2Te3 nanoplates and nanoflowers: Synthesized by hydrothermal process and their enhanced thermoelectric properties

Abstract

Bi₂Te₃ nanoplates with a thickness of 15–20 nm and self-assembled flower-like nanostructures using previous nanoplates as building blocks have been fabricated through a low-cost hydrothermal method with ethylenediamine tetraacetic acid (EDTA) as an additive. The structures and morphologies of the samples were characterized viaX-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectrometry (FT-IR) and transmission electron microscope (TEM) measurements. The growth mechanisms have been proposed based on the experimental results. The nanoplates and flower-like Bi₂Te₃ nanocrystals (NCs) with no residual additives were consolidated by high pressure to an n-type nanostructured bulk material with preserved crystal grain sizes. Moreover, self-assembly NCs show higher thermoelectric properties than the nanoplates. The power factors and thermoelectric figure of merit (ZT) of chemically synthesized flower-like Bi₂Te₃ NCs were improved up to 8.6 μW cm⁻¹K⁻² and 0.7, respectively, which possess the potential to design new materials and devices for thermoelectric applications.