Template-Free Electrochemical Synthesis of High Aspect Ratio Sn Nanowires in Ionic Liquids: A General Route to Large-Area Metal and Semimetal Nanowire Arrays?

A facile low-temperature and template-free synthesis route to high aspect ratio Sn nanowires is described. The nanowires are prepared by electrochemical deposition from SnCl4/ionic liquid solutions containing SiCl4 onto a variety of substrates, including glassy carbon as well as Cu, Al, and Sn foils. SiCl4 is found to strongly promote the growth of nanowires under specific conditions, while only bulk structures are achieved in the absence of SiCl4. The nano-wires exhibit a unique hair-like morphology with very high areal density (>= 5 X 10(9) cm(-2)), and they have diameters in the sub-30 nm size range over lengths of up to 90 mu m, leading to aspect ratios as high as 5 X 10(3). Diffraction, spectroscopy, and microscopy studies establish that the nanowires are of high quality and consist of single phase, anisometric beta-Sn crystallites. The morphology of the deposits is very uniform over centimeter-sized areas and can be tailored by changing key parameters such as the concentration of SiCl4 and/or SnCl4 and the electrode potential. Perhaps more importantly, this approach is not restricted to the synthesis of Sn nanowires and can be applied to other metals and semimetals with an anisotropic crystal structure (e.g., Zn and Te).