Polymer-modified electrodes advantages

The different fields of application have demonstrated the advantages of the new ESR-electrochemical cell for simultaneous studies in radical formation and reaction at solid electrodes as well as in studies of polymer modified electrodes. 

Table 2.3 gives results of a calculation carried out by Albery and Hillman that show optimum layer thickness values for optimal mediated electrocatalysis. We can perform some very simple calculations to obtain quantitative estimates of the catalytic advantage of using a polymer-modified electrode with results from Table 2.3. Albery and Hillman assume that typically for efficient mediation k ME must be ca. 10 cms Furthermore the rate constant for the mediated process at the polymer-coated electrode Atme must be greater than that for the direct unmediated process k. We see from Table 2.3 that when W 1, the optimum case is LSk, with k ME = kKXEbo and L 3Xe- When V = 1, L Xo Xl and k ME = kK XoXi) b(i- Furthermore when F 1, the optimum...

We have sought to exploit the advantages of polymer modified electrodes for the determination of transition metal ions and organic functionalities [18-23]. Our methods are based on the preconcentration of the analyte (metal ion or organic functionality) at the electrode surface by modifying the same with functiondized polymers that carry reagents for the selective and sensitive determination of the species of interest. 

Application of transition metal hexacyanoferrates for development of biosensors was first announced by our group in 1994 [118]. The goal was to substitute platinum as the most commonly used hydrogen peroxide transducer for Prussian blue-modified electrode. The enzyme glucose oxidase was immobilized on the top of the transducer in the polymer (Nation) membrane. The resulting biosensor showed advantageous characteristics of both sensitivity and selectivity in the presence of commonly tested reductants, such as ascorbate and paracetamol. 

While the structure of nonredox polymer and polyelectrolytes thin layers has received much attention in the past [116, 117], only recently has a molecular theory able to treat, from a molecular point of view, redox polyelectrolytes adsorbed on electrodes, been presented [118-120]. The formulation of the theory, its scope, advantages and limitations will be discussed in detail in Section 2.5.2, and therefore we will limit ourselves to show here some predictions that are relevant for the understanding of the structure of polyelectrolyte-modified electrodes. The theory was applied to study the particular system depicted in Figure 2.5, which consists of a single layer of PAH-Os adsorbed on a gold surface thiolated with negatively charged mercapto... 

Through the combination of SPR with a - poten-tiostat, SPR can be measured in-situ during an electrochemical experiment (electrochemical surface plasmon resonace, ESPR). Respective setups are nowadays commercially available. Voltammetric methods, coupled to SPR, are advantageously utilized for investigations of - conducting polymers, thin film formation under influence of electric fields or potential variation, as well as - electropolymerization, or for development of -> biosensors and - modified electrodes. Further in-situ techniques, successfully used with SPR, include electrochemical - impedance measurements and -+ electrochemical quartz crystal microbalance. 

Our approach to the color-variable LEDs presented here has a number of important advantages (1) The two redox polymers modify the charge-inj ection properties of the polymer/metal interfaces, allowing the use of high-workfunction metals as electrodes. This potentially reduces the aging problems associated with conventional polymer LEDs, which must use reactive low-workfunction metals to... 

Using preformed redox polymers as electrode modifiers has the advantage of completely characterizing polymers prior to modifying the electrode surface. Control of the layer thickness of the deposited films can be achieved by carefully controlling the amount deposited by using drop- or spin-coating procedures. 

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