Many researchers have reported that the size of counter electrode should be larger than size of working electrode. At present I am using 1 cm2 metal oxide coated carbon cloth as working electrode and Pt wire as counter electrode therefore I want to know that whether size of electrodes really matters ? If yes, Can I used Copper Plate as counter electrode instead of Pt wire for CV/GCD Study in 2M KOH electrolyte for ultracapacitor ?
You can use a graphite rod or plate as the counter electrode with a large area in contact with the electrolyte. Even better, you can make a graphite container (box or cylindrical shapes are both good) for the liquid electrolyte and at the same time use it as the counter electrode.
For common uses, only a few precious metals, e.g. Pt and Au, are electrochemically stable enough to be used for making the counter electrode. Thus, carbon based materials, particularly graphite, are the more economical choice. However, there are of course exceptions. For example, lithium metal is very offen used as both the reference and counter electrode in studying lithium ion battery materials.
Dear Chirag Mevada,
Mainly when we do impedance analysis (EIS), we need high area of the counter electrode.
Because both the working and counter electrode are connected in series and if the area of the counter electrode is very high and capacitance will be also high and effective capacitance will be negligible as it is connected in series. Therefore contribution from the counter electrode will be negligible in the impedance spectrum.
Another thing is that counter electrode should be highly conducting materials and if area is high then resistance will be less and it can collect current more effectively.
Pt is very stable materials and it will not react with electrolyte that easily.
Yes, you can use other stable metal as counter electrode but make sure there is no reaction or dissolution happen in the metal.
Best Regards,
Bapi
Dear Sir,
Thanks for sharing your thoughts. If possible than kindly suggest me suitable stable metal which can withstand for 1 M Na2SO4 and 2M KOH electrolyte.
using copper plate will be a bad idea as there is high chance of reacting with the electrolyte.
You can use a graphite rod or plate as the counter electrode with a large area in contact with the electrolyte. Even better, you can make a graphite container (box or cylindrical shapes are both good) for the liquid electrolyte and at the same time use it as the counter electrode.
For common uses, only a few precious metals, e.g. Pt and Au, are electrochemically stable enough to be used for making the counter electrode. Thus, carbon based materials, particularly graphite, are the more economical choice. However, there are of course exceptions. For example, lithium metal is very offen used as both the reference and counter electrode in studying lithium ion battery materials.
Yes, you can use other metal as a counter electrode povided that it should not react with the electrolyte and it should be stable in the medium under your consideration.
Graphite carbon can be the preferable selection as compared to the copper.
Copper is not the suitable choice as counter in your system as this may react with the electrolyte and may affect the kinetic response of your working electrode. For this purpose, Graphite or inert metals would be the suitable choices. Also the counter electrode surface area should be at least 1.5 to 2 times larger than the working electrode exposed area to avoid any influence of the counter electrode in the kinetic response of the working electrode.
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