• Boulanger, Clotilde
• Stein, Nicolas
• Szymczak, Jonathan
• Diliberto, Sébastien
• Legeai, Sophie

Abstract

Tellurium (Te) and its alloys present interesting physical properties (electric, thermal, optoelectronic) and are used in many applications such as photoconductors, piezoelectric devices, thermoelectric generators and coolers. At the nanoscale, Te and its compounds are more efficient compared to bulk materials. Te-alloys nanostructures are obtained, in most cases, from Te nanowires, which synthesis represents then a great interest. Electrochemical deposition (ECD) is a low cost technique widely used in literature for the synthesis of nanostructures. Arrays of 1D nanostructures are usually synthesized by template-assisted electrodeposition method, using anodic aluminium oxide (AAO) or polycarbonate membranes templates. However, nanowires are embedded in the template leading to limitations for further applications. A template-free synthesis route would then be more convenient, cheaper and easier to perform. In this work, we report on the template-free synthesis of Te nanowires from the 1-ethyl-1-octylpiperidinium bis(trifluoromethylsulfonyl)imide ionic liquid (EOPipTFSI). To our knowledge, no study has been reported on the template-free ECD of 1D nanostructures in room temperature ionic liquids (RTILs). This class of electrolytes presents some interesting properties for ECD purposes. Their high thermal stability, allowing ECD at elevated temperatures (up to 250°C), could open the door for a one step elaboration of materials of high cristallinity. Moreover, metallic precursors can reach high solubility values in RTILs, typically higher than 0.1 M. In the case of Te deposition, this represents a great advantage compared to aqueous media in which Te precursors are poorly soluble leading to low growth rates. In the electrolyte used in this work, Te(IV) concentration can reach 90 mM. Analytical voltammetric, potentiometric and amperometric studies were realized to determine kinetics and thermodynamics characteristics of the electrochemical systems involved. Our results show that Te nanowires arrays can be electrodeposited by adjusting experimental parameters. The morphology and the structure of the deposits have been investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Depending on the electrolyte temperature and composition, the coatings can be constituted from Te nanowires perpendicular to the substrate. Transmission electronic microscopy (TEM) reveals that the nanowires are single-crystalline and grow along the [001] direction

Topics

• impedance spectroscopy
• morphology
• compound
• scanning electron microscopy
• x-ray diffraction
• aluminum oxide
• aluminium
• transmission electron microscopy
• electrodeposition
• Tellurium