Its better to use the new one.

I found that you can reuse it but you will need to make sure it is cleaned and the surface is well activated. I use this method :

10 min in a 1M NaOH solution in a ultrasonic bath

10 min in a EtOH in a ultrasonic bath

10 min in a deionized water solution in a ultrasonic bath

and you are good to go

I would not generally prefer to reuse ITO, but if you must make sure its cleaned as much as possible. If the ITO was just used bare (without anything coated) for your study, re-using is fine. However, if you have something (like say TiO2) coated on top of ITO, I strongly advise you not to trying to clean it off and reuse it since it is both time consuming and very difficult to get the ITO surface clean (depending on your coating parameters).

Your cleaning agents will depend on the nature of chemicals exposed to ITO (say the coating or the electrolyte). I generally sonicate ITO in DI water, acetone, ethanol and Isopropanol for 15 min each, followed by surface activation in UV for 15 min (optional depending on ur exp). If you already have something coated on that you need to remove, extend your sonication times and make sure you have the stuff removed (or use a stripping procedure to remove it). Also, make sure to re-check the resistance of ITO and see if there was some damage. 

Of course, if you have a sketchy surface, that will show up quite clearly when you measure your electrochemical response. In my opinion, a used ITO plate would be good for initial data collection and trial and error stuff. However, when you are checking for reproducibilty or publications etc, you would want to use a fresh, perfectly cleaned ITO

Congrats -arun

My sample is fine powder (Pd/Al2O3), if i deposit a thin layer over Indium foil (not IOT) and use it as working electrode, will it work in CV? And what could be the preferred electrolyte solution. Suggestion from expert in the field