What are the arguments of making a distinction between the CE and RE if I am measuring non-faradaic processes (i.e. binding events to a surface modified WE)? I understand the arguments for faradaic measurements, that the CE allows current to pass while to ensure the RE can maintain a constant potential. However, if no current is flowing across my electrode interface(s), why would a 3-electrode benefit?
Three-electrode configuration allows you to better control what is happening on working electrode. e.g. apply a DC bias to polarize the working electrode for certain purpose. Also, you are able to focus on the change on working electrode and neglect the effects from counter electrode if you are only interested in working electrode.
What do you mean by " no current is flowing across my electrode interface"?
Dan
Indeed you can use a two electrode system, it won't make much difference, since you have a very small capacitive currents. Also it depends on your applied DC bias and frequency. For a short time and large polarization potential it does make a difference if you use 2 or 3 electrode system. But for better control of your polarization potential and insulating the effect of counter electrode, it is better to use three electrode system.
Success,
Yawar
Dan and Yawar, Thank you for your responses.
I am interested in using the sensor for non-faradaic purposes. In my system, I am only applying small AC potentials (10 mV) with a 0 V DC offset from OCP. Since I am using noble metal electrodes, I am assuming charge transfer across my interface is negligible.
Hunter
Since you are interested in using the cell as a sensor, then if you could use a small AC (only) current iAC-mode (iDC=0), you might avoid any (noisy and/or growing) DC current from an OCP potential variation(s) as side-effects in common V-mode due to some reasons (temperature, pressure, external fields, etc.).
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