Electrochemical impedance spectroscopy coating capacitance

Finally, electrochemical impedance spectroscopy (EIS) can be used to quantify the impedance characteristics of a CP. The vast majority of literature has shown that CP coating of conventional electrode materials can reduce the interface impedance by several orders of magnitude [12,52,79,139]. This has widely been attributed to the increase in surface area available for charge transfer when CPs are employed. Importantly, EIS is also used to model the electrode interface. CPs reportedly alter the capacitive behavior of conventional electrode materials to produce a predominantly resistive interface with significantly smaller phase angles at low frequencies [12,51,139,140]. 

Electrochemical Impedance Spectroscopy. Electrochemical Impedance Spectroscopy (EIS), a non-destructive investigative technique enables an insight into the corrosion process not obtained by DC techniques. EIS provides information on reaction parameters, corrosion rates, oxide characteristics and coating integrity, data on electrode interfacial capacitance and charge transfer resistance. It provides... 

Since wet adhesion is critical for corrosion protection, techniques for studying wet adhesion can be useful. Electrochemical impedance spectroscopy (eis) is used to study coatings on steel. Many papers (99,100) are available, covering various applications of eis. When a coating film begins to delaminate, there is an increase in apparent capacitance. The rate of increase of capacitance is proportional to the amount of area delaminated by wet adhesion loss. Onset of delamination can be determined by eis studies (101). Results of eis tests are subject to considerable variation (102). Other problems with eis are discussed in Reference 103. 

Electrochemical impedance spectroscopy is useful in the evaluation of coatings, the elucidation of transport phenomena in electrochemical systems, and the determination of corrosion mechanisms and rates. Bode and Nyquist plots are the most common data output formats, and an example of each for a simple parallel-connected resistance-capacitance circuit are shown in Figs. 31.3, and 31.4, respectively. The Bode plot format shows the... 

Dispersion — Frequency dispersion results from different frequencies propagating at different speeds through a material. For example, in the electrochemical impedance spectroscopy (EIS) of a crevice (or porous) electrode, the solution resistance, the charge transfer resistance, and the capacitance of the electric double layer often vary with position in the crevice (or pore). The impedance displays frequency dispersion in the high frequency range due to variations in the current distribution within the crevice (pore). Additionally, EIS measurements in thin layer cells (such as electrochromic devices, conducting polymer-coated electrodes, ion-... 

Norlin A, Pan J, Leygraf C (2002) Investigation of interfacial capacitance of Pt, Ti and TiN coated electrodes by electrochemical impedance spectroscopy. Biomol Eng 19(2-6) 67-71, URL http //www.biomedsearch.com/nih/Investigation-interfacial-capacitance-Pt-Ti/12202164.html... 

Evaluation of the volume fraction of water in organic coatings in immersion is often made by electrochemical impedance spectroscopy, EIS, and based upon the evolution of the coating capacitance. Among the several models and equations proposed for this determination, the most frequently used is the Brasher equation. Most... 

Electrochemical measurements with the thiol-coated gold surface acting as an electrode can provide very important information about the integrity and order of the monolayer . Two main phenomena are usually used for monolayer characterization capacitance measurements (with cychc voltammetry or impedance spectroscopy) and heterogeneous electron transfer (cychc voltammetry). The electrode in contact with solution acts as a capacitor whose capacitance strongly depends on the distance between the electrolyte and the metal surface, i.e. the thickness of the monolayer . Therefore, for well-packed monolayers which are impermeable for electrolyte, the measured capacitance can be used to calculate the thickness of a monolayer. These data are usually in good agreement with the thickness measured by other methods. 

---