Hello, I am just getting into electrochemistry and would like to ask for help, please.
I have an oxidation reaction which is not spontaneous.
1- My supervisor told me that I should do a ciclic voltammetry to find the potential at which the reduction reaction takes places, which is not spontaneous, to yield an specific product. I found it, with an associated current.
2- I'd need to peform the reaction over time, not just to monitor the potential and associated current by ciclic voltammetry. If the reaction is a reduction one, it needs electrons, so, do I have to fix the current to provide the system with electrons? or do I have to fix the potential and record the intensity? In the first case, which is the name of the technique in a conventional potentiostat device?
Thank you very much, really appreciate your help.
Manuel
Hello Mv Gomez
In order to monitor the reduction of your redox species using cyclic voltammetry you would first need to scan over a wide range of potential (1V to -1V). Also if the concentration of your species is relatively high you could also use a high scan rate to get a better peak current value (100 mV/s for example).
Afterwards, you will potentially have a peak at a specific potential Epc. Then if you just want to perform the reduction of your species you could use chronopotentiometry (E=f(t) at a fixed current I) or chronoamperometry (I=f(t) at a fixed potential E). The fixed values of I and E would need to be located between 1/3 and 2/3 of the E range comprising the beginning of the reduction and the Epc.
Best regards,
Marie B.
Thank you Marie, really useful information.
If you let me, I would ask you another question, please.
I have two reaction pathawys in the global system, which are:
- reduction of oxygen to water
- oxidation of an complex organic molecule as a result of a catalysis process.
The catalyst takes electron from a donor (in my case current from potenciostat), and then oxidizes my molecule through a catalysis process and gives the electron to the oxygen as a final terminal, which is reduced to form water.
In such case, if a want my organic molecule to be oxidized, do I have yo fix the potencial and current of oxidation I get from ciclyc voltametry? Or those of oxygen reduction?
Dear Mv Gomez
Yes, you need to fix the potential and current of oxidation that you get from cyclic voltammetry (If your aim is to study the oxidation of an organic complex molecule in presence of catalyst). Because your oxidation of an organic molecule happen at working electrode and we controlled the potential and current of the working electrode. And as a counter part of the reaction oxygen reduction to water will happen at counter electrode.
Best Regards,
Bapi
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