Electrode-electrolyte interface, chemical kinetic models

In conclusion, the study of the overall process of electrochemical formation of polypyrrole must include not only the simple oxidation of monomer and the coupling of the charged species to produce the polymer chains, but also the nature, kinetics and effects on polymer structure and properties of all the parallel electrochemical and chemical processes which accompany it. Models of interfacial reactions, including the different processes taking place at the electrode/ electrolyte interface, must be developed showing the possibilities for the use of electrochemical methods of synthesis to obtain specific polymer films for each technological application. 

Because the Adler model is time dependent, it allows prediction of the impedance as well as the corresponding gaseous and solid-state concentration profiles within the electrode as a function of time. Under zero-bias conditions, the model predicts that the measured impedance can be expressed as a sum of electrolyte resistance (Aeiectroiyte), electrochemical kinetic impedances at the current collector and electrolyte interfaces (Zinterfaces), and a chemical impedance (Zchem) which is a convolution of contributions from chemical processes including oxygen absorption. solid-state diffusion, and gas-phase diffusion inside and outside the electrode. 

While thermodynamics provides a starting point, kinetics is essential for providing any corrosion model of practical utility. The term electrode kinetics is often used as, in the electrochemical paradigm, the oxidation and reduction occur at independent sites, which can be considered as separate electrodes marking a solid/electrolyte interface at which the half-ceU reactions take place. In the case of chemical corrosion, these half-cell reactions can take place at the same location, in which case there is no external current flow between the half-reaction centers, but instead, direct charge transfer between the reactants via electronic contact at the same metal site. 

Nanoscale modeling methods, such as molecular dynamics (MD) and DFT, aim to understand the kinetics of the electrochemical and chemical reactions on the electrode surfaces and at the interfaces between the electrodes and electrolyte, and the conduction processes in the electrolyte and the electrodes. 

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