Template-assisted nanostructuring metals

Wire-shaped growth of nanostructured PPy with diameter <10 nm, has been obtained by electropolymerization at naturally occurring step defects and artificially formed pit defects of HOPG, in a template assisted electropolymerization where the size of the nanostmctures could be controlled by limiting the pyrrole polymerization time at anodic potentials [242], Electrochemical polymerization of pyrrole within the confines of anodized alumina templates and subsequent metal nanoparticles immobilization on the surface of polymer pillars has been used to make surfaces that show roughness on two independently controllable levels sub-microscopic roughness from polymer pillar dimensions and nanoscopic roughness from the appropriate size selection of metal NPs [243],... 

Abstract Electrodeposition is a weU-known conventional surface modification method to improve the surface characteristics, decorative and functional, of a wide variety of materials. Now, electrodeposition is emerging as an accepted versatile technique for the preparation of nanomaterials. Work done in this direction is discussed in this chapter. The basics of electrodeposition are introduced, then the electrodeposition of nanomaterials using special techniques for reducing grain size. Methods such as pulse and pulse reverse current deposition, template-assisted deposition and use of additives and grain refiners are explained with suitable examples. Deposition of nanostructured metals, alloys, metal matrix composites, multilayers and biocompatible materials reported in the literature are discussed. Finally, there is a discussion of the improved corrosion resistance of electrodeposited nanostructured materials, quoting results reported in Uterature. 

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. 

Fig. 1 Examples of morphologies of semiconductor nanostructures, (a) metal assisted Si etching and formation of Si-NWs. Electrochemical formation of (b) microporous silicon, (c) ZnO nanorods, (d) porous CdSe using porous alumina template, (e) CdTe nanowires using alumina template, (1) CdS nanowires using alumina template, (g) mesoporous Xi02 film using doctor blade method, (h) self-ordered anodic Xi02 nanotubes and (i) cross section image of the same Xi02 nanotubes (reproduced with permission from Ref. 8,27,28,45 8).

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