Why is there no saturation current for Si photoanode during OER?

[Amy_chen]

TL;DR Summary

Hello all,
When I investigate an oxygen evolution reaction (OER) performance of Si/Ni photoanode for water splitting, there is no saturation current in LSV lines. I don't understand why. Thank you so much.

The Si/Ni photoanode was prepared by sputtering Ni on n-p homojunction Si substrate, and the electrolyte was KOH solution.

 

[Valerie Park]

The sputtering process involves depositing a thin layer of Ni onto the n-p homojunction Si substrate by bombarding it with energetic particles, such as argon ions. This creates a strong adhesion between the Ni and the Si substrate, resulting in an efficient transfer of electrons between the two materials. After sputtering, the Ni/Si photoanode is then immersed in a KOH solution to form the electrolyte. The KOH solution facilitates the transfer of electrons from the photoanode to the electrolyte, allowing for the generation of electrical energy.