Dear Dr. Armita Farsiani

You can observe cathodic and anodic peaks together in CV, but in SV you can observe one of each processes (cathodic or anodic) as you choose, and decide according to inputs you gave for software.

Regards

Thanks for your answer.

The point is, I haven't changed any parameter in CV, but only the sweep voltages. Before, with different sweep parameters, I have got both anodic and cathodic peaks in CV and now by narrowing sweeping voltages range, I'm not able to see both anodic and cathodic reactions in one measurement.

Thanks for your answer :)

There is a problem here... when I sweep voltages betwen the values that you have mentioned (0...0.4v....-0.4v....0), What I get is only cathodic peak, as seen in the attached images.

But when I sweep between the voltages that I optimized (0v....0.8v...-1.5v ...0) I'm able to see both cathodic and anodic peaks.

Actually it is important for me to be able to see both peaks in smaller range of voltage (I changed the sensor sizes as well, but no improvement...)

Do you know why in smaller range of voltages, both peaks can not be detected? Michal Hanko

Hello Michal,

Thanks for your answer :) I proceed with the measurements and let you updated about the results. It's a 2 electrode setup, RE and CE as one unit and the electrolyte is Methylene Blue in PBS buffer. The electrodes are made of gold.

As you mentioned, there is a shift in all the cycles. Do you possibly know what the reason can be? Michal Hanko

Hello, Armita!

From your previous answer, it is still not clear which electrodes were used, what is your working electrode? To study the electrochemical behavior of methylene blue, a three-electrode setup must be used.

Hello Irina,

The electrodes that I used are gold Cu Be alloy, covered with gold.

Actually I was running the experiment with 2 electrode and 3 electrode setup (In two electrdoe setup RE and CE probes of potentiostat were connected together). According to the results, I decided to go for two electrode setp since it provided me with the best signal and higher SNR.

Do you have an idea how to amend the results?

I started using 3 electrode setup now and with MB, here are the results. My CE and RE electrodes are both Cu BE gold covered electrodes. As the experiment is running for more than 10 minutes with the same probe, I noticed that there is a very thin black color on my electrodes.

Can it be the copper that oxidises in the reaction? (However, after cleaning the surface with IPA, the black layer is disappeared.)

In the graphs I still can see the current shift after running few cycles. This can happen, as you mentioned, as a result of change in concentration profile of the oxidation, then. Michal Hanko