Polymer electrodes special modifications

SPECIAL MODIFICATIONS WITH ELECTROACTIVE POLYMER FILMS Bilayer Electrodes... 

In supercapacitors, apart from the electrostatic attraction of ions in the electrode/electrolyte interface, which is strongly affected by the electrochemically available surface area, pseudocapacitance effects connected with faradaic reactions take place. Pseudocapacitance may be realized through carbon modification by conducting polymers [4-7], transition metal oxides [8-10] and special doping via the presence of heteroatoms, e.g. oxygen and/or nitrogen [11, 12]. 

In the case of polymers or solid supports, intrinsic functionalities can sometimes be used as anchoring groups for the coupling with biomolecules. In other cases suitable functional groups must be introduced by substitution or activation. Several excellent reviews on the chemical modification of electrodes have covered all possibilities in this respect [250-254]. For special emphasis, modiflcation procedures are shown here that may play a role in electrochemical biosensor development on the basis of different electrode materials (Figure 14-16). 

He has pubhshed approximately 50 papers in international peer-reviewed journals and two book chapters. Dr. Terzi has been invited to hold seminars and to be Guest Editor for special issues of international journals. He visited the Laboratory of Materials Chemistry and Chemical Analysis (University of Turku, Finland) and the Department of Chemistry (University of Oxford, UK) in order to broaden his knowledge on surface characterization techniques. His main scientific interests are (i) the modification of electrode surfaces using conducting polymers, self-assembled monolayers, (nano)particles, and graphene (ii) the spectroscopic and microscopic characterization of the electrode coatings (iii) the synthesis and characterization of (nano)particles (iv) electrocatalysis applied to amperometric sensors. 

Trogadas and Ramani summarized the modification of PEM membranes, including Nafion modified by zirconium phosphates, heteropolyacids, hydrogen sulfates, metal oxides, and silica. Membranes with sulfonated non-fluorinated backbones were also described. The base polymers polysulfone, poly(ether sulfone), poly(ether ether ketone), polybenzimidazole, and polyimide. Another interesting category is acid-base polymer blend membranes. This review also paid special attention to electrode designs based on catalyst particles bound by a hydrophobic poly-tetrafluoroethylene (PTFE) structure or hydrophilic Nafion, vacuum deposition, and electrodeposition method. Issues related to the MEA were presented. In then-study on composite membranes, the effects of particle sizes, cation sizes, number of protons, etc., of HPA were correlated with the fuel cell performance. To promote stability of the PTA within the membrane matrix, the investigators have employed PTA supported on metal oxides such as silicon dioxide as additives to Nafion. 

Surface-modified electrodes — In order to alter the properties of an electron-conducting substrate, i.e., a metal or graphite or semiconductor used as a part of an electrode, different chemical compounds are produced/deposited/attached/immobilized on the surface. These electrodes are most frequently called surface-modified, chemically-modified, or polymer-modified electrodes, depending on the methods and materials used for the modification. The obvious purpose of these efforts is the production of electrodes with novel and useful properties for special applications, but also to help gain a better understanding of the fundamental charge transfer processes at the interfaces. Usually the enhancement of the rate of the electrode reaction... 

The preparation of electrochromic, solvent-processable, thiophene-based polymers allowed electrode modification (e.g., upon spray casting) [539-541]. At the same time, the color of the film could be switched electrochemicaUy. In addition, special derivatives of polyaniUne [542] showed a multielectrochromic behavior (Fig. 48) [543, 544]. 

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