This article reviews a general template-based approach for the
preparation of nanomaterials. The method involves the synthesis of a
desired material within the pores of a nanoporous membrane. We have termed
this approach ‘template synthesis’ because the pores within
these nanoporous membranes act as templates for the synthesis of
nanostructures of the desired material. Because the pores within these
membranes are cylindrical and of uniform diameter, monodisperse
nanocylinders of the desired material are obtained. Depending on the
chemistry of the pore wall and material, these nanocylinders may be either
hollow (a tubule) or solid (a fibril or nanowire). This template process
will be shown to be a very general approach in the fabrication of
nanotubes and fibrils composed of a variety of materials including
polymers, metals, semiconductors, carbons, and other
materials.

A general template-based method for the preparation of nanomaterials

: An electroless deposition procedure for filling the pores in nanoporous filtration membranes with metal (gold) nanowires is described. This method allows us to routinely prepare ensembles of gold nanodisk electrodes in which the nanodisks have diameters as small as 10 nm. Results of electrochemical experiments at ensembles of 30 nm-diameter and 10 nm-diameter gold-disk electrodes are described. The electrochemical response characteristics of these nanoelectrode ensembles are in agreement with predictions of the relevant electrochemical theories. Cyclic voltammetric detection limits for electroactive species at ensembles containing 10 nm-diameter gold disks can be as much as 3 orders of magnitude lower than at a large-diameter gold-disk electrode.

Fabrication and evaluation of nanoelectrode ensembles

Multivariate instrument standardization

In the 1950s and 1960s fundamental developments in electrochemical methods included voltammetry and low signal techniques. A generation later, the discovery of the unusual properties of ultramicroelectrodes has opened new possibilities of analyzing electrode processes. The changes in mass transport conditions bring about extremely high current densities at ultramicroelectrodes, whereas the currents themselves become very small. This little-noticed phenomenon allows for many electroanalytical applications that are not possible with conventional electrodes, especially experiments in solutions with very low electrolyte concentrations, in nonpolar solvents, in solids, and even in gases. In addition, two factors— changes in the experimental time scale at low scan rates because of the size of the electrode, and insignificant iR effects at very high scan rates—make it possible to study very fast homogeneous and heterogeneous electrode processes.

Ultramicroelectrodes in Electrochemistry

M.I. Montenegro

Papers

The determination of the kinetics of electron transfer using fast sweep cyclic voltammetry at microdisc electrodes

Studies of electrode reactions in low ionic strength media using microelectrodes

Deprotection by electrolysis

Ultramicroelectrodes for the study of the mechanism of electrosynthetic reactions: the hydrodimerisation of acrylonitrile

Further studies of the reduction of styrene in toluene/N, N-dimethylformamide mixtures