Luminescent polycrystalline cadmium selenide nanowires synthesized by cyclic electrodeposition/stripping coupled with step edge decoration

摘要

Cadmium selenide (CdSe) nanowires, 30-300 nm in diameter, were synthesized using electrochemical step edge decoration on highly oriented pyrolytic graphite (HOPG) surfaces. These CdSe nanowires were more than 100 mu m in length and were organized into parallel arrays of hundreds following the length and organization of the HOPG step edges used to nucleate these nanowires. The synthesis of CdSe nanowires involved a method derived from the cyclic electrodeposition/stripping scheme described by Sailor and co-workers (Chem. Mater. 1991, 3, 1015). Stoichiometric CdSe was obtained by electrodepositing CdSe together with excess elemental cadmium and selenium, followed by the selective oxidative stripping of both excess cadmium and selenium from these nanowires. This synthesis method also afforded precise control of the nanowire diameter over the above-mentioned range. CdSe nanowires were characterized by scanning electron microscopy, transmission electron microscopy (TEM), selected area electron diffraction, photoluminescence, X-ray photoelectron spectroscopy, and Raman spectroscopy. The TEM results showed that the CdSe nanowires were composed of nanocrystalline, cubic CdSe with a crystallite size that decreased with increasing pH. CdSe nanowires showed band edge photoluminescence at 1.74 eV that increased in intensity by a factor of 15 when these wires were covered by a shell of CdS by exposure to gaseous H2S at 300 degrees C.