Preparation of CdS Single‐Crystal Nanowires by Electrochemically Induced Deposition

Abstract

In the past few years, attention has been focused on the research field of one-dimensional nanostructural materials, both because of their fundamental importance and because of the wide range of potential applications in nanodevices.[1±12] Many attempts have been made to fabricate onedimensional nanostructure materials utilizing a variety of nanofabrication techniques and crystal growth methods. [1,5,6,13±20] However, it is still a challenge to synthesize an aligned and well-distributed single-crystal nanowire array. Electrochemical synthesis using a template is one of the most efficient methods for the growth of nanowires because the growth occurs almost exclusively in the direction normal to the substrate surface. [20] In addition, anodic aluminum oxide possesses uniform and nearly parallel porous structures; hence they have been used as an ideal template to produce cylindrical nanowires with a narrow diameter distribution. As CdS is one of the most important II±VI group semiconductors, having vital applications in solar cells and optoelectronic and electronic devices, the AC electrodeposition of CdS nanowires in porous anodic aluminum oxide (AAO) templates has been investigated.[21±23]However, structural studies have demonstrated that large numbers of stacking faults and twinned segments are present in these nanowires. [23] Recently, an aligned CdS singlecrystal nanowire array has been produced using DC electrolysis in AAO templates from a dimethylsulfoxide (DMSO) solution containing cadmium chloride and elemental sulfur.[24] Here we report a new electrochemical process to prepare CdS single-crystal nanowires using electrochemically induced deposition [25] in the pores of an AAO template from an acidic chemical bath containing cadmium chloride and thioacetamide (TAA). The details of the growth of the AAO templates, the deposition of the CdS, and the characterization of the nanowires can be found in the Experimental section. Figure 1a shows a typical transmission electron microscopy (TEM) image of CdS nanowires prepared by electrochemically induced deposition in the AAO template with pore diameters of about 90 nm. It can be seen that the diameter of the nanowires is about 90 nm, which corresponds to the diameter of the pores of the template used. The lengths of the nanowires range from 3 to 5 mm after deposition for 8 h. Figure 1b shows a TEM image of the nanowires deposited in the template with pore diameters of about 20 nm; the uniform diameters of about 20 nm and smooth surfaces are clearly visible. After deposition for 8 h, the length of the nanowire is up to 10 mm, which is 2±3 times as long as the nanowires deposited in a template with pore diameters of 90 nm under the same deposition conditions. This experimental result indicates that the growth rate of the nanowire increases with decreasing pore size of the AAO template.The chemical composition of the nanowires was determined using X-ray energy dispersion analysis (EDAX) and Raman spectroscopy. The EDAX spectrum shown in Figure 2a reveals that the nano...

One‐Dimensional Semiconductor Nanowires: Synthesis and Raman Scattering

“…For instance, Lieber and coworkers reported on electrically driven CdS nanowire lasers. [46] To date, various methods have been reported for the synthesis of CdS nanowires, such as hydrothermal/solvothermal routes, [47] in situ micelle-template-interface reaction processes, [48] ion beam synthesis, [49] ultrasonic irradiation, [50] microwave-assisted techniques, [51] hard template method, [52] and vapor transportation techniques. [53] Stable and homogeneous CdS nanowires have been successfully obtained in aqueous SDS solutions.…”

Template-Assisted Electrochemical Synthesis of Semiconductor Nanowires

“…As the reaction occurs inside the cylindrical pores, the wire diameter is controlled by the pore size, which grows from the surface of the electrode to the top of the template. However, Xu et al [32] used an aqueous solution containing CdCl 2 and thioacetamide to produce CdS NWs onto AAO membranes at 70 o C. The overall reaction for the CdS NWs growth is written as eq. (3) [33].…”

Cataluminescence and Catalysis Properties of CO Oxidation Over Porous Network of ZrO2 Nanorods Synthesized by a Bio-Template

“…Over the past few years, much research attention has been paid to one-dimensional nanostructures because of their potential applications in nanodevices [1][2][3]. It is well known that the properties of materials can be influenced by their physico-chemical structures.…”