Nanowire template-based

One-dimensional (1-D) nanosbuctures (b) are composed mainly of nanowires, nanorods and nanobelts. Spontaneous growth, template-based synthesis and electrospinning are considered bottom-up approaches, while lithography is a top-down technique [7, 84]. Two-dimensional (2-D) nanostructures (c) involve thin films, which have been the object of intensive study for almost a century and for which many methods have been developed and improved. 

The nanostructures can be deposited into the nano-pores by electrodeposition or sol-gel deposition methods. The advantages of being low cost and repeatable, together with their potential compatibility with silicon technologies, make these nanostructure synthesis procedures interesting. Despite its simplicity, template-based growth is characterized by the production of polycrystalline nanowires, which can limit their potential for both fundamental studies and applications. 

X. Yu, Y. Li, and K. Kalantar-zadeh, Synthesis and electrochemical properties of template-based polyanihne nanowires and template-free nanofibril arrays Two potential nanostructures for gas sensors. Sens. Actuators B, 136, 1-7 (2009). 

Semiconducting one-dimensional (ID) nanolibers or nanowires are of interest for a wide variety of applications including interconnects, functional devices, and molecular sensors as well as for fundamental physics studies. Devices have been fabricated fi om semiconductor, and carbon nanotubes, and more recently from ICP nanofibers. It has been predicted that ICP nanofibers will have unique electrical, optical, and magnetic properties [134]. Several different methods for producing these ICP nanofibers have been developed with or without the aid of a template. The template-based methods involve synthesizing a tubular structure of the ICP within the pores of a support membrane, such as an alumina membrane [135] or a track-etched polycarbonate membrane [136]. However, more recent work has... 

A variety of solution methods such as seed-assisted growth, template-based synthesis, polyol method, solvothermal method and oriented attachment have also been developed for the synthesis of one-dimensional nanostructures. Here we will present various examples of the nanowires including metals, oxides, chalcogenides and pnictides with different synthetic methods. 

Hu J, Odom TW, Lieber CM (1999) Chemistry and physics in one dimension synthesis and properties of nanowires and nanotubes. Acc Chem Res 32 435 45 Hulteen JC, Martin CR (1997) A general template-based method for the preparation of nanomaterials. J Mater Chem 7 1075-1087... 

Liana DD, Raguse B, Gooding J.J J, Chow E (2012) Recent advances in paper-based sensors. Sensors 12 11505-11526 Lim MA, Kim DH, Park C-O, Lee YW, Han SW, Li Z, Williams RS, Park 1 (2012) A new route toward ultrasensitive, flexible chemical sensors metal nanotubes by wet-chemical synthesis along sacrificial nanowire templates. ACS... 

Cochran, R.E., Shyue,).-). and Padture, N.P. (2007) Template-based, nearambient synthesis of crystalline metal-oxide nanotubes, nanowires and coaxial nanotubes. Acta Materialia, 55,... 

Besides the aforementioned templates, many other research groups have developed their own template-based electrochemical synthesis techniques. For example, photolithography methods such as the lithographically patterned nanoscale electrodeposition (LPNE) method developed by Penner are excellent ways to produce nanostructures with controllable dimensions. - With this process, the Penner group has been able to produce nanowires with length scales in the macroscale while still maintaining precise control over the nanowires height and width with resolutions in the tens of nanometers." ... 

Cao G, Liu D (2008) Template-based synthesis of nanorod, nanowire, and nanotube arrays. Adv Colloid Interface Sci 136 45-64... 

Porous aluminum oxide can be used as a template for the production of nanowires and nanotubes. For example, metals can be deposited on the pore walls by the following procedures deposition from the gas phase, precipitation from solution by electrochemical reduction or with chemical reducing agents, or by pyrolysis of substances that have previously been introduced into the pores. Wires are obtained when the pore diameters are 25 nm, and tubes from larger pores the walls of the tubes can be as thin as 3 nm. For example, nanowires and nanotubes of nickel, cobalt, copper or silver can be made by electrochemical deposition. Finally, the aluminum oxide template can be removed by dissolution with a base. 

Au-nanopartide nanowires based on DNA and polylysine templates. Angewandte Chemie-International Edition, 41, 2323-2327. 

Over the past few years, a large number of experimental approaches have been successfully used as routes to synthesize nanorods or nanowires based on titania, such as combining sol-gel processing with electrophoretic deposition,152 spin-on process,153 sol-gel template method,154-157 metalorganic chemical vapor deposition,158-159 anodic oxidative hydrolysis,160 sonochemical synthesis,161 inverse microemulsion method,162 molten salt-assisted and pyrolysis routes163 and hydrothermal synthesis.163-171 We will discuss more in detail the latter preparation, because the advantage of this technique is that nanorods can be obtained in relatively large amounts. 

Our approach utilized the metals gold, platinum, then later gold, platinum, and nickel electroplated in succession because the catalytic decomposition of hydrogen peroxide reaction we tested was most efficiently catalyzed with platinum.After fabrication of the nanowires they were freed by removing the conductive silver backing with nitric acid and the sacrificial template with a strong base, sodium hydroxide. Then nanorods were washed with deionized water and ultracentrifuged to achieve a neutral pH. 

Similar approach has also been taken by Ferain and Legras [133,137,138] and De Pra et al. [139] to produce nanostructured materials based on the template of the membrane with etched pores. Polycarbonate film was also of use as the base membrane of the template, and micro- and nanopores were formed by precise control of the etching procedure. Their most resent report showed the successful formation of ultrasmall pores and electrodeposited materials of which sizes were as much as 20 nm [139]. Another attractive point of these studies is the deposited materials in the etched pores. Electrochemical polymerization of conjugated polymer materials was demonstrated in these studies, and the nanowires based on polypyrrole or polyaniline were formed with a fairly cylindrical shape reflecting the side wall structure of the etched pores. Figure 10 indicates the shape of the polypyrrole microwires with their dimension changes by the limitation of the thickness of the template. 

The synthesis of conductive metallic nanowires that bridged two microelectrodes separated by a gap of 12-16 im was demonstrated by the growth of a silver nanowire on a DNA template that bridged the gap (Fig. 12.26).92 Short thiolated nucleic acids (12 bases long) were attached to the microelectrodes, and these acted as sticky ends for the hybridization of /.-DNA that bridged the gap. The association of Ag+ to the phosphate groups of the template, followed by their reduction with hydroquinone under basic conditions, resulted in the formation of Ag° nanoclusters on the DNA template. The subsequent enlargement of the Ag° seeds by the catalytic reduction of Ag+ by hydroquinone, under acidic conditions, yielded continuous Ag nanowires with a width of ca. lOOnm. The nanowires revealed nonlinear I—V... 

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