If I am depositing a material on top of a metal electrode, it is expected that the resistance increase and the conductance decrease, right? can the opposite happen too? is there any explanation to that behavior?
It depends on what do you deposit. In the following cases the conductivity increases:
- the coating (generally metallic) has a more conductance than the substrare
- the conductance of the two materials is almost the same but you increase the surface area (dendritic deposition)
- the coating catalyzes some reactions
I strongly agree with Mr. Giurlani,
if you deposit an electrically non-conductive material, normally the electrical conductance of the electrode should extremely diminish.
However, if an electrically conductive material, such as Nanoparticles possessing high surface to volume ratio and electron transfer capacity is embedded at the electrode surface, bring out a significant increase in the conductivity of the electrode.
As is well known, Room Temperature Ionic Liquids as an ultra-high electrically conductive material as compared to Non-conductive mineral oil (Paraffin) owing to its high electron transfer capacity, has a great influence on the sensitivity of carbon paste electrodes.
Impedance spectroscopy is an appropriate analytical method to characterize the mentioned properties of electrode ingredients in terms of conductivity.
For more Info.s about this topic you can consider our papers.
In a deposition experiment, the measured current is indicative for the reaction rate at electrode, not for the electrode/deposit bulk resistance (commonly it is not a limiting factor).
The variation of the effective reaction area at electrode must be considered first.
In a general case, a current decrease may be observed due to the electrode polarisation.
Yes I agree with above. In many cases depositing other materials is used to enhance the conductivity.
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