Electrodeposition of high aspect ratio single crystalline tellurium nanowires from piperidinium-based ionic liquid

Template-free electrodeposition of high aspect ratio Te nanowires is presented. Nanowires were obtained from the ionic liquid 1-ethyl-1-octyl-piperidinium bis(trifluoromethylsulfonyl)imide (EOPipTFSI) containing 1-ethyl-1-octyl-piperidinium bromide (EOPipBr). The influence of the EOPipBr content on the dimensions and the morphology of the nanostructures was studied. Several micrometers long tellurium nanowires with diameters between 100 and 180 nm were obtained when the EOPipBr content of the electrolyte is higher than 0.5 mol%. By decreasing the bromide concentration, the electrochemical behavior of TeIV solutions becomes more complex, leading to several reduction signals. By varying the applied overpotential, hair-like single crystalline nanowires can then be obtained with a diameter which can reach 50 nm and a length of 70 μm leading to a high aspect ratio of almost 2000. High Resolution Transmission Electron Microscopy analyses show that the nanostructures are single crystalline and reveal a growth along the c-axis, with a smooth interface. No surface contaminants were observed by Scanning Transmission Electron Microscopy, proving that halide ions do not play the role of capping agents.