Ag/AgCl has been deemed as a suitable reference electrode for photoelectrochemical water splitting studies under AM 1.5 G and UV light irradiation. A number of previous studies have reported its use in PEC studies. I have been using Ag/AgCl (in 3M KCl) for water splitting studies under neutral and mildly alkaline conditions (pH 7-8), and notice a slight but well defined color change to a brown color upon prolonged AM 1.5 G illumination. This is pretty interesting, and I would like to hear if any of you had noticed this (or is it some mistake on my experimental plan!!)
Considering the fact that AgCl itself is photoactive and is known to photodecompose upon visible and UV radiation, could this be a case of photodecomposition? Moreover, Ag/AgCl and AgCl by itself has also been used as photocatalyst for dye degradation. Considering these aspects, can we now begin doubting the reliability of the Ag/AgCl reference for PEC water splitting studies??
Ag/AgCl is suitable to be used in solar water splitting. If the color changes, it means the formation of AgOH or Ag2O. Especially in alkaline solution (e.g. Na2S + Na2SO3) it is pretty easy to grown to brown color under long time illumination. So we shielded it from the light illumination and check it is good after the PEC performance experiments.
Ag/AgCl electrode is suitable to be used in solar water splitting. There are some precautions before using it, for example, the electrode must be shielded from the light source to avoid its decomposition or converting it into oxide. Also it can be used in alkaline solution( e.g. NaOH) pH = 13.9 but the connection of membrane should be fitted with the glass to prevent its corrosion by sodium hydroxide.
Ag/AgCl is suitable to be used in solar water splitting. If the color changes, it means the formation of AgOH or Ag2O. Especially in alkaline solution (e.g. Na2S + Na2SO3) it is pretty easy to grown to brown color under long time illumination. So we shielded it from the light illumination and check it is good after the PEC performance experiments.
The suitable way to use Ag/AgCl electrode in photoelectrochemical reaction is to shield it, just as Mahmoud Elbaz and Qing Kang's answers. Another way is to use a salt bridge and a Luggin capillary, which is my recommendation. In this way, you can put your Ag/AgCl electrode somewhere safe.
So simple, as long as you get 197 mV (max 10 mV error but stable) from the Ag/AgCl ref electrode, it's OK.
I even use it from pH 4 to 11, or some time in 0.1M OH, no problem.
Just, from time to time, check potential of you ref electrode.
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