Soft chemistry synthesis route toward Bi₂Te₃ hierarchical hollow spheres

Hollow spheres made of Bi₂Te₃ nanoplatelets were successfully synthesized using a low temperature, wet chemical synthesis route. By using a one-pot synthesis, large quantities of microspheres, arranged in a gypsum flower manner, can be obtained in about 1 h. The mechanism leading to such a particular morphology has been deeply studied by both solid and solution characterization techniques (X-ray diffraction, scanning and transmission electron microscopy, X-ray fluorescence, ¹H nuclear magnetic resonance spectroscopy) which were carried out at different stages of the synthesis. The key points are the generation of alcanethiol-in-polyol droplets and the subsequent in situ controlled interfacial reaction between Te and Bi precursors. The Te(IV) ions present in the alcanethiol phase are initially reduced into Te(0) by decanethiol. The Bi(III) ions initially dissolved in the polyol phase are then reduced at the decanethiol/polyol interface, resulting in the progressive growth of Bi₂Te₃ hexagonal nanoplatelets at the outer surface of the pristine Te(0) sphere.