Low temperature reduction route to synthesise bismuth telluride (Bi₂Te₃) nanoparticles: structural and optical studies

Abstract

Herein, we report the synthesis of highly yielded bismuth-telluride (Bi 2 Te 3 ) nanoparticles at 50 C by direct wet chemical route in which the bismuth and tellurium precursors have been dissolved in deionised water, ethylene glycol and hydrazine hydrate. This method is very facile, inexpensive and less hazardous and ensures almost complete yield of the precursors. The powder product was well characterised by powder X-ray diffraction, UV-Vis spectroscopy, Fourier transform infrared spectroscopy, energy dispersive X-ray diffraction, transmission electron microscopy and scanning electron microscopy. It is investigated that the synthesised powder has a rhombohedral structure of Bi 2 Te 3 with average diameters of the particles about 35 nm. Thus, the synthesis process has been modified to design nanostructures of thermoelectric materials with related crystal structures.Keywords: nanostructures; chemical synthesis; electron microscopy; X-ray diffraction; optical properties IntroductionTransition-metal chalcogenides in nanocrystalline form exhibit numerous interesting and useful characteristic properties that differ from their bulk counterpart. As a consequence of the quantum confinement effect, nanomaterials have received attention due to their size-dependent optical, physical, mechanical, thermal and chemical properties. During the past few decades, with the rapid enlargement of human population, the consumption of traditional energy has increased exponentially. Therefore, more and more researchers come to pay close attention to new sources of energy. Thermoelectric (TE) device emerges as a new kind of hot substance that can directly achieve the conversion between heat and electricity, which can maximise the use of waste heat and electricity in daily life. TE materials can convert waste heat energy to useful electrical energy for power generation and imperative applications in thermoelectric micro-cooling devices. The properties of a TE material can be explained by the energy conversion efficiency which mainly depends on the material's dimensionless TE figure-of-merit (ZT) ¼ sS 2 T/k, where s is the electrical conductivity, S is the Seebeck coefficient, T is the operating temperature and k is the thermal conductivity. The quantity 'S 2 s' is commonly considered as 'power factor'. An increment in power factor and a decrease in thermal conductivity are essential requirements for the enhancing ZT value. For a fine TE material, it posses high 's' and a low 'k'. Spongy TE materials [1] such as skutterudites [2] and clathrate crystals [3]

Few-layer hexagonal bismuth telluride (Bi2Te3) nanoplates with high-performance UV-Vis photodetection

“…1g ) were calculated based on the results in Fig. 1f , and size-dependent E g values of 0.83 eV (Bi 2 Te 3 NPs-1) and 1.0 eV (Bi 2 Te 3 NPs-2) were obtained, close to that of the previously reported Bi 2 Te 3 nanoparticles, 42 suggesting that the E g of Bi 2 Te 3 NPs could be easily controlled by simply tuning the reaction conditions.…”

Ab initio investigations on the structural and optical properties of sol-gel synthesized bismuth telluride nanoparticles

“…The energy dispersive study of nano Bi 2 Te 3 using its x-ray spectrum is depicted in figure 6. According to the elemental analysis, the atomic percentage of Bi and Te were 37.59% and 62.41% respectively, which is well accordance with the reported value [24].…”

Mass production of 2D materials by intermediate-assisted grinding exfoliation

“…S12 and previous reports [ 38 , 39 ]). In addition, for Bi 2 Te 3 the appearance of a prominent absorption peak at 265 nm reveals the production of few-layer 2D Bi 2 Te 3 [ 40 ]. These results confirm that the iMAGE-produced 2D materials have good structural integrity rather than having been functionalized.…”