Template-Assisted Electrochemical Growth of Cu Nanorods and Nanowires

Template-Assisted Electrochemical Growth of Cu Nanorods and Nanowires 

The first study to describe this approach can be traced back to a report by Penner and Martin, who studied the deposition of Pt-nanowires into the pores of alumina [337]. Subsequently, the method was investigated in great depth by several other groups, and recently employed specifically for the preparation of Cu nanorods, nanotubes and nanowires [338-343]. In fact, almost all template electrochemical depositions lead to supported or membrane-embedded nanostmctures. As mentioned in Section 1.1, the aim of this chapter is to review only self-standing nanomaterials, and for this reason in the following sections particular attention will be paid to those approaches targeted at the production of unsupported nanomaterials, such as those which include an additional step to dissolve the membrane. 

Investigations have been conducted with polycarbonate track-etched templates, aluminum oxide membranes and nonporous mica [344-352], and in all cases the nanomaterial preparation consists primarily of a controlled electrodeposition of copper from a precursor solution (usually CUSO4) inside the nanochannels of the template. In a second step, the template is removed, thus releasing the elongated nanostructures. By following this approach, Gao and coworkers [353] prepared dense and continuous copper nanowires which were 30 xm long and had a uniform 

A further means of gaining control over the diameter and diameter-dependent optical properties of Cu nanowires was proposed by Duan and coworkers [356], who identified a relationship between nanowire diameter and template etching time. By following this approach, they obtained Cu nanowires with a peculiar X-ray diffraction (XRD) pattern, which was suggestive of a preferential growth direction. They also observed a significant red-shift of the surface plasmon resonance peak as the wire diameter was increased. 

Nanowires grown by the use of template-directed protocols usually possess a high degree of crystallinity. In particular, Gao and coworkers [353] demonstrated that a suitable choice of potential values during electrochemical deposition allowed the predictable synthesis of either single-crystal or polycrystaUine copper nanowires. 

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