Preparation And Microstructure Control Of One-dimension Tellurium Based Core-shell Heterostructure Thermoelectric Nanomaterials

In recent years, due to the increasingly prominent of the global energy crisis, environmentaldegradation, more and more attention of the potential applications of thermoelectric materials for powergeneration and thermoelectric cooling has been paid. Research on thermoelectric materials and theirapplications has become a hot topic in many countries. Development and utilization of the semiconductorthermoelectric materials have important practical significance for the energy use, economic developmentand environmental protection.In this paper, the Te nanowires/rods were firstly synthesised by microwave-assisted wet chemicalmethod. Subsequently, Bi, Bi₂Te₃and Sb₂Te₃were in situ deposited on the surface of Te nanowires/rods,and one-dimensional Te/Bi, Te/Bi₂Te₃and Te/Sb₂Te₃core-shell heterostructure thermoelectric materialswere obtained. The effect of microwave-assisted wet chemical process on the phase and microstructure ofthe products and the growth mechanism of the one-dimensional core-shell heterostructures wereinvestigated.With increasing of the PVP concentration, the structure of the Te nanowires was more uniform, morenarrow grain size distribution; with decreasing of the hydrazine hydrate dropping rate, the uneven degree ofthe nanowires increased; with increasing of reaction temperature, the diameter of the nanowire was thicker,shorter length, smaller aspect ratio; with incresing of reaction time, the obtained small "triangle" disk nucleigrew into a "bud", and these bud grew into the "slub" shaped nanotubes with the intermediate solid andhollow morphology at both ends, then these nanotubes adsorpted the Te atoms and grew into the structuralintegrity nanowires by capillary effect.One-dimensional core-shell heterostructures Te/Bi, Te/Bi₂Te₃and one-dimensional single-phaseBi₂Te₃could be obtained by controlling reaction time. When the Bi precursor solution was added into theprepared Te nanowires, one-dimensional core-shell heterostructure Te/Bi can be obtained when the reactionwas incubated for0minutes at160°C; one-dimensional core-shell heterostructure Te/Bi₂Te₃could beobtained when the reaction was incubated for30minutes at160°C; one-dimensional single-phase Bi₂Te₃could be obtained when the reaction was incubated for60minutes at160°C.When the Bi₂Te₃precursor solution was added into the prepared Te nanowires, the Bi₂Te₃moleculeswould nuclei and deposit on radial and both ends of the the Te nanowire, epitaxially grew and formed thewrapped core-shell heterostructure. The Core-shell heterostructure Te/Bi₂Te₃nanowire whose intermediateradial attached with a large number of ultra-thin nanosheets and ends was like "mushroom-shaped" couldbe obtained.When the Sb₂Te₃precursor solution was added into the prepared Te nanowires, the Sb₂Te₃moleculeswould nuclei and deposit on radial of the the Te nanowire, epitaxially grew and formed the wrappedcore-shell heterostructure, core-shell Te/Sb₂Te₃heterostructure nanowire could be obtained.When glycerol was used as the solvent, the single-phase Sb₂Te₃nanotubes could be obtained bydirectly reducing TeO2and SbCl3with microwave-assisted wet chemical method.