Hello experts,
I am using a rotating cylinder electrode (2000 rpm) iron in a sodium sulfate solution. I collect chronoamperometric data (the applied step potential is in a range of +60 to +100 mV vs. OCP). The current data is collected for 0.1 seconds and the data acquisition rate is every 10 to the minus 5 sec (10^-5 sec). It means 10000 data points per 0.1 sec. In some of my current responses, after the initial jump of the current, I see that the current remains constant for few microseconds (please see image below)--the current values remain constant up to 5 decimal numbers. I use GAMRY 600 Ref. potentiostat instrument. Solution resistance is about 0.7 ohm. Using a calibration Dummy cell, this constant current region did not show up. So, I guess there is something about my experimental setup or measurements that I need to change to fix this issue, but I don't know what that is.
Any idea about how I can fix this? Thank you in advance
Mohin
Dear Mohiedin Bagheri Hariri ,
try to reduce[1] the Area, A->Amin, of the WE, either by
1) elevating the WE, or by
2) reducing the volume of the electrolyte,
and remeasure the same.
.
1. reduce (towards a minimum A.min) the Area, A, of the WE (iron) in contact with the electrolyte (sodium sulfate solution).
Dear Dr. Ioannis Samaras ,
Thank you very much for your reply. What do you mean elevating the WE? I really appreciate your reply.
Mohin
Dear Mohiedin Bagheri Hariri ,
maybe you just need to set a higher measuring current range or use auto-ranging if this function exists ?
Best regards,
Nicolas
Dear Dr. Murer,
Thank you for your message.
I tried it but still, the instrument is struggling to collect the current signal for few microseconds (sampling period is 2*10^-6 sec per data point). I tried the calibration Dummy cell, even using calibration cell it seems that the Gamry 600 potentiostat struggles to monitor response for few microseconds when I step potential from an initial value to the next step potential.
Best regards,
Mohin
Mmh, OK. Unfortunately, I don't know well enough Gamry products to precisely answer your question...
What I know though is that some techniques are faster than others and that using a fixed current range instead of auto will increase the time response of the instrument.
Using a fast bandwidth will also increase the instrument speed.
Finally, there is one specification of interest for you it is the slew time. Maybe what you are trying to do is beyond the instrument capabilities.
I think the best for you is to contact your local Gamry representative, :-).
Al the best,
Nicolas
Thank you Nicolas for your guidance.
Yes, you are correct. Slew time and changing the speed setting might help.
I think I need to change these parameters in the script of the framework for GAMRY so the instrument can capture those data.
Thank you so much for your reply.
Regards,
Mohin
Дорогой Мохиендин,
без эквивалентной схемы мне трудно судить о причинах генерации наблюдаемого дополнительного постоянного напряжения.
Поэтому могу предложить лишь общие соображения надо разделить
1. его генерацию электродом
2. переходные характеристики измерительной схемы
3. наводки.
И начать с того, полагаю, что надо собрать эквивалентную схему и подав на неё меандр с низкочастотного генератор провести измерения
Уважаемый доктор Ордин, Stanislav Ordin
Спасибо за ваш ответ. Я действительно ценю это.
Конечно, я попробую это посмотреть, поможет ли это. Я провел тест с калибровочной ячейкой, но все равно получил тот же ответ. Я применяю потенциальный шаг и хочу отслеживать текущий отклик с высокой частотой дискретизации.
С уважением,
Mohiedin
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