I was trying to find a way to accurately report the onset potential but could not come across any accurate definition of when how to report it. The most conveniently way I came across was to report when a non-zero (anodic) current starts to flow. I'm currently investigating doped and non-doped CuWO4 for water splitting applications. For the non-doped sample, the photocurrent is higher the dark current at zero photocurrent density, But for the doped sample this is not the case. Why is happening? Am I measuring the onset potential incorrectly?
Hi Ganesh,
I read the paper and they describe using scanning electrochemical
microscopy (SECM) to determine the onset potential. It doesn't answer my question, however. Interesting read though
Hi,
Basically there are three ways to measure onset potential in photoelectrochemical water splitting systems.
We can take the potential at the intersection point of the tangent at maximum slope of photocurrent and the dark current curve as onset potential and this is the common way many people have reported. It might be convenient for you to use this so that you can easily compare with other similar reports.The potential at which the photocurrent exceeds a certain defined value or the potential at which dj/dv exceeds a certain defined value are also considered as onset potential. However, it must be bear in mind that all these methods are somewhat arbitrary and may be more or less appropriate depending on the shape of the J-V curves at hand.
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