Nanostructured Metal Filaments

More than 20 years ago, Matsushita et al. observed macroscopic patterns of electrodeposit at a liquid/air interface [46,47]. Since the morphology of the deposit was quite similar to those generated by a computer model known as diffusion-limited aggregation (D LA) [48], this finding has attracted a lot of attention from the point of view of morphogenesis in Laplacian fields. Normally, thin cells with quasi 2D geometries are used in experiments, instead of the use of liquid/air or liquid/liquid interfaces, in order to reduce the effect of convection. 

A simple model was proposed on the basis of the experimental findings, in which the solution pH plays a key role for the oscillatory instability [51]. The theoretical 

Raman Microspectroscopy Study of Oscillatory Electrodeposition of Au at an Air/Liquid Interface 

As has been shown above, oscillatory electrodeposition is interesting from the point of view of the production of micro- and nanostructured materials. However, in situ observation of the dynamic change of the deposits had been limited to the micrometer scale by use of an optical microscope. Inspections on the nanometer scale were achieved only by ex situ experiments. Thus, information vdth regard to dynamic nanostructural changes of deposits in the course of the oscillatory growth was insufHcient, although it is very important to understand how the macroscopic ordered structures are formed with their molecular- or nano-components in a self-organized manner. 

Surface-enhanced Raman scattering (SERS) is a candidates for resolving this issue. Since the SERS effect is observed only at metal surfaces with nanosized curvature, this technique can also be used to investigate nanoscale morphological structures of metal surfaces. It is thus worth investigating SERS under oscillatory electrodeposition conditions. The author of this chapter and coworkers recently reported that 

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Other groups like those of Belloni or Doudna also applied -y-radiolysis to reduce metals. Most of the systems reported by these groups were metallic alloys with catalytic applications. Recently, Doudna et al. reported a method based on radiolytic reduction to generate filament-like nanostructures of Ag Pt. 

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