I try to determine the Tafel constants as well as the exchange current density from potentiodynamic current density-potential curves for an electrolyte mainly composed of 0.3M CuSO4 and 1.9M H2SO4.
For this experiments I used a rotating disk electrode (brass) as working electrode, a big plate of copper (I also tried once a Pt electrode) as counter electrode and a Ag/AgCl electrode (3M KCl) as reference electrode.
The experiments have all been conducted in a faraday cage.
Each curve I receive has some of these steps, also at different rotating speeds.
This phenomenon only occurs when I use the rotating disk electrode. Other experiments (LPR measurement, potentiodynamic current density-potential curves, EIS) without rotating disc electrode work very well.
It would be great if anybody out there has an idea what could be the reason for this issue.
Thanks a lot.
It is difficult to answer this question with such limited diagnostics. Sometimes automatic change in the Current-to-Voltage converter gain causes steps in current, and they usually do occur in decade steps like yours. I would suggest doing a CV scan with a fixed Current-to-Voltage setting. If the steps disappear, you have your culprit.
Аномалии могут возникнуть из-за кислорода в растворе или продуктов окисления меди растворенным кислородом, из-за примеси-деполяризатора в растворе или из-за неплотности внутри дискового электрода, через которую в раствор попадает что-то совсем не то, что нам хотелось бы.
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