I'm running a charge-discharge analysis using autolab. I have a problem where it creates a bubble on the counter Pt electrode and after 500 cycles the working electrode is etched on the electrolyte.. Does anybody have a solution for me?
I think your problem is that the surface area of your counter electrode (CE) is not sufficiently high.
There is the same current on CE passing as on working electrode, WE (opposite sign, of course). Thus, if you increase the surface area of CE without changing the surface area of WE, the current density on CE will be lower. Thus, hydrogen will rather be dissolved in electrolyte and diffuse away than be accumulated into the gas bubble. It might be even possible to avoid hydrogen generation on CE, if its surface is very high.
Try platinizing your CE. With potentiostatic platinization from PtCl6^2- or PtCl4^2- solutions you can increase surface area aspect by factor 100 or more.
You are may be using more potential range than required. change the potential range.
I think you use Pt plate, try Pt wire, it´s better. I had bubbles on Pt plate when nitrogen bomb was finishing:)
If you use platinum wires (or gauze) instead of Pt sheet or foil, there will be formation of very small gas bubbles. When you use plain sheet or foils, the interfacial tension between the plain sheet ( CE) and the gas film is less and big bubbles are formed . When rods or wire type configurations are used (CE), the interfacial tension between rod/wire and the gas film is higher and lead to smaller bubble formation. That is how the design of anodes/cathodes are made for modern filter press type rectangular electrolysers.
On all analysis, i'm using Pt wire..increasing potential range will affect on hydrolysis of aq. electrolyte..it forming small bubble and want to reduces or eliminate..i should do oxygen removal perhaps.
Prior to every measurement I remove oxygen by bubbling by Ar or N at minimum 15 minutes, it depends on type of used electrolyte
I think your problem is that the surface area of your counter electrode (CE) is not sufficiently high.
There is the same current on CE passing as on working electrode, WE (opposite sign, of course). Thus, if you increase the surface area of CE without changing the surface area of WE, the current density on CE will be lower. Thus, hydrogen will rather be dissolved in electrolyte and diffuse away than be accumulated into the gas bubble. It might be even possible to avoid hydrogen generation on CE, if its surface is very high.
Try platinizing your CE. With potentiostatic platinization from PtCl6^2- or PtCl4^2- solutions you can increase surface area aspect by factor 100 or more.
Increasing the surface area of the counter electrode seems to be the most effective way out this problem, however if it is possible to use rotating or at least moving or shaking counter electrode then you can avoid the gas accumulation on the surface. Stirring the solution is also useful sometimes if you dont have to work at stationary electrolyte.
Please mention which electrolyte and WE you are using in your work. Any how you have mentioned CE. If the electrochemical reaction leads to evolution of H2 in such case in order to reduce hydrogen evolution you may have to chose appropriate electrode such as BDD which has high value of hydrogen over potential. In order to reduce O2 evolution it is better to add some additives which can help as a scavanger of oxygen. But the additive should not interfere in electrolysis. Moreover instead of static electrolysis use a stirrer during electrolysis.
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