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electrochemical reaction

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Rashmeet
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Joined: September 15th, 2021, 10:26 am
Country: United States

electrochemical reaction

Post by Rashmeet » September 15th, 2021, 10:41 am

I want to do a electrochemical operation using reference and working electrode. I have keithley 2636B and I want to use this for my measurements. please can anyone tell that how to set the keithley where I give some voltage through keithley and see the current reading in keithley that is flowing in my electrochemical cell.
your help is highly appreciate.

KMittaaja
Posts: 4
Joined: September 3rd, 2021, 12:08 am
Country: Finland

Re: electrochemical reaction

Post by KMittaaja » September 20th, 2021, 5:13 am

The basic problem in your idea is that you really have a three electrode cell: counter (CE), working (WE) and reference (REF) electrodes.
You measure electrochemical potential between reference electrode and working electrode.
You feed current between counter electrode and working electrode, to alter the aforementioned potential.
Reference electrode is high-impedance device so feeding current through it is not possible - nor wanted.

So you would really need two channels (one between CE-WE, another between REF-WE) and use one channel for feeding current (and measuring the current), and the other for measurement (electrochemical potential). Of course, it is a non-linear function, how feeding current will affect the electrochemical potential, so you would really need a controller that takes as an input the potential (ref-we) and as output controls current (ce-we). This device, doing all this, is called potentiostat!

I'm not really familiar with 2636B but if it has two separate floating channels, you might be able to do the thing with potential measurement at one channel (ref-we) and polarization at the other channel (ce-we), and use some external software to do the potential control (via instrument bus) by controlling polarization current to achieve wanted potential. You might use PID control algorighm for that.

Of course, buying a potentiostat would be quite a bit cheaper and faster, considering the price of around 20ke for 2636b. :)

Andrea C
Keithley Applications
Keithley Applications
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Re: electrochemical reaction

Post by Andrea C » September 27th, 2021, 12:46 pm

Rashmeet,

If it is just a two electrode cell, then you could do it with two cables from the back of 2636B.
Choose SMUA or SMUB.

Connect LO to Reference Electrode.
Connect HI to Working Electrode.

This two wire connection will lump the I*R drops of the cables with your cell.
To eliminate that consider enabling 4-Wire Remote Sense and running four cables:

Connect LO and Sense LO to Reference Electrode.
Connect HI and Sense HI to Working Electrode.

Andrea

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