Electrically active polymers Electrodes

A more favourable approach is the incorporation of the active species in an electrically conducting polymer layer which then acts as an (electrical) intermediate between the electrode surface and the catalyst. Polypyrrole is considered to be especially suitable because it is acceptably stable under ambient conditions (2), has a high conductivity and can be easily prepared electrochemically from a great variety of solvent systems, including aqueous solutions (3-5). The catalytic species that have been applied in such polypyrrole-based systems comprise metal particles (6-9), metal chelates (10-13) (with anionic side groups) and enzymes (14-18). 

In order to satisfy the industrial demand, the performance of supercapacitors must be improved and new solutions should be proposed. The development of new materials and new concepts has enabled important breakthroughs during the last years. In this forecast, carbon plays a central role. Due to its low cost, versatility of nanotextural and structural properties, high electrical conductivity, it is the main electrode component. Nanoporous carbons are the active electrode material, whereas carbon blacks or nanotubes can be used for improving the conductivity of electrodes or as support of other active materials, e.g., oxides or electrically conducting polymers. 

The alignment and electrical contacting of NAD -dependent enzymes on electrodes was also accomplished by the generation of the NAD enzytne complex and its crosslinking on a conductive, redox-active, polymer that electrically contacts the cofactor-enzyme assembly with the electrode, Fig. 3-23. 

This chapter reviews in detail the principles and applications of heterogeneous electron transfer reaction analysis at tip and sample electrodes. The first section summarizes the basic principles and concepts. It is followed by sections dedicated to one class of sample material glassy carbon, metals and semiconductors, thin layers, ion-conducting polymers, and electrically conducting polymers. A separate section is devoted to practical applications, in essence the study of heterogeneous catalysis and in situ characterization of sensors. The final section deals with the experiments defining the state of the art in this field and the outlook for some future activities. Aspects of heterogeneous electron transfer reactions in more complex systems, such as... 

The Faradaic activity of thin films of pol3nneric phthalocyanines 31 (M = Cu(II)) on titanium foils in electrochemical cells has been investigated [94]. Electrodes with the polymer film dipped into an aqueous solution of K3Fe(CN)6/K4Fe(CN)6 exhibit a high Faradaic activity and reversibility comparable to a bare platinum electrode. The electrically conductive polymer allows an efficient electron transfer to redox couples in solution. Thin films of... 

Most work related to the covalent labeling of proteins with organometallic is related to the development of enzyme or antibody amperometric biosensors. For the majority of redox enzymes, the active center (or redox-aetive cofactors) are buried inside the protein and are therefore electrically inaccessible for direct electron transfer to the electrode surface of an amperometric biosensor. This problem has been resolved by (i) addition of a diffusional redox-active mediator, (ii) covalent tethering of the mediator to the protein, or (iii) immobilization of the protein in a redox-active polymer. Ferrocenyl derivatives have frequently been used in all three formats as mediators because of their almost ideal electrochemical properties. 

Kumar, Y, G. P. Pandey, and S. A. Hashmi. 2012. Gel polymer electrolyte based electrical double layer capacitors Comparative study with multiwalled carbon nanotubes and activated carbon electrodes. Journal of Physical Chemistry C 116 26118-26127. 

Lim, C. S., K. H. Teoh, C. W. Liew, and S. Ramesh. 2014. Electric double layer capacitor based on activated carbon electrode and biodegradable composite polymer electrolyte. Ionics 20 251-258. 

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