Polycrystalline platinum and gold

The screen-printed approach for depositing thin films of metal has become popular in recent years. This approach is especially useful for producing multiple electrodes on a substrate or electrode array structures. Patterns are photolithographicaUy formed on a screen, whose mesh contains open and blocked zones. An ink containing the metal of interest is applied to the screen and forced through the open zones onto the substrate using a squeegee blade. Once the solvent has been evaporated (air dry or an oven cure), the electrode is ready for use. In the CVD approach, molecules of a volatile precursor are transported in a carrier gas to a heated substrate. The compounds reach the substrate and react to form the desired metal film. 

In the case of platinum, chromium is also used as an adhesion layer as are niobium and titanium (128). For this metal, chemical treatments have also been developed for the removal of adhesion layer contaminants (129). 

Solvent cleaning or solution soaking should also be effective at activating the metal electrodes, although one must be careful about the molecular adsorption of some solvent types 

Laser irradiation has been used by McCreery and coworkers to activate platinum electrodes (132). This involves applying pulses from a Nd YAG laser (1064 nm) to the electrode immersed in a supporting electrolyte solution. The laser beam diameter is a few mm and output powers of 5-100 MW cm can be employed. Importantly, the activation was performed in the presence of a few mM of CN anion. Several researchers have reported that CN stabilizes k° for Fe(CN)6 by forming an adlayer that prevents electrode 

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