LIGA-electrodes in voltammetric and spectroelectrochemical studies

The advantages of lithographic-galvanic (LIGA) fabricated microstructured h oneycomb electrodes are demonstrated for spectroelectrochemical cells with respect to the response time (the time necessary to generate the product in a sufficient layer thickness close to the electrode to be detectable by UV -Vis-NIR spectroscopy) and to the conversion of the redox system in solutio n under thin-layer conditions. Transmission UV-Vis-NIR spectroscopy for sev eral electrochemical applications can be performed in a special spectroelec trochemical cell based on the LIGA electrode and the two quartz rods, formi ng the walls of the cell and conducting the light beam through the cell. Th ey are limiting the diffusion layer at the structured part of the working L IGA electrode. These microstructured LIGA-electrodes can be used as well de fined models of porous electrodes at which redox processes occur under fini te diffusion conditions. Such electrodes have been successfully used in the voltammetric and spectroelectrochemical study of various redox systems in both aqueous and non-aqueous solvents. The possibility to fabricate the wel l defined microstructures from various organic conducting polymers is demon strated by the electrochemical deposition of polypyrrole in moulded LIGA-fo rms at high current densities in aqueous solutions.