Electrochemistry : characterizing the electrode-electrolyte

AI Thread Summary
The discussion centers around the modeling of the electrode-electrolyte interface in electrochemistry, specifically using a metallic electrode in deionized water. The user references "Modern Electrochemistry 2A: Fundamentals of Electrodics" by Bockris, noting that the interface can be represented as a parallel circuit of resistance and capacitance. The interfacial resistance and the electrical double layer (EDL) capacitance are key components in this model. The user questions whether the commonly accepted EDL capacitance value of approximately 20 µF/cm², typically observed in higher ionic concentration solutions, can be applied to their scenario involving deionized water and direct current (DC). They express concern that the absence of ions in deionized water may significantly alter the capacitance, leading to a potentially lower value. The discussion highlights the complexities of estimating EDL capacitance in low-ionic environments and the implications for their work on streaming current.
Florent
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Hello guys (and gals),

I have mostly a background in Physics, but I've recently had to get some knowledge on electrochemistry, and more precisely on electrode-electrolyte interface.

From "Modern Electrochemistry 2A : Fundamentals of Electrodics" by Bockris I gathered that in the case of a metallic electrode plunged in an aqueous solution (with ultradilute concentration of inorganic ions) with a DC current, I can pretty much model it with a resistance and capacitor in parallel as an equivalent electrical circuit with the resistor being the interfacial resistance and the capacitor being the EDL capacitance.

From what I gathered, the capacitance of the EDL of a metallic electrode is generally estimated to be around 20µF/cm² in solutions with millimolar to molar concentration of ions with AC current. Can I safely take this value (or this order of magnitude) for my electrode in deionized water and DC or am I missing an important parameter that can change everything ?

Hope I'm making sense :p
Cheers !
 
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μF or pF/cm2?
 
µF/cm² for differential capacitance at least
 
Last edited:
Florent said:
deionized water
??!
 
Yes, I'm working on streaming current and on the data with deionized water as fluid
 
EDL involves ions and water dipoles, no ions, much less pronounced EDL.

At least that would be my line of thinking.
 
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