In PEC water splitting, the most common substrate used is ITO or its FTO. Being conductive in nature they are useful in transferring electrons from semiconductor to outer circuit but what purpose it serves being transparent in nature especially when we are only concerned with front side illumination (Light falling on semiconductor).
It makes me more curious since ITO is really expensive and we have so many better-conducting cheaper alternatives such as carbon paper, stainless steel etc.
In fact, ITO or FTO is not the necessary substrate in PEC water splitting. we can use other suitable electrode materials. But, FTO and ITO have many advantages as the substrate, such as very stable in relatively high temperature (less than 600 ) and various electrolyte, easy for deposition. For example, photoelectrode materials are difficult to deposit on carbon cloth due to its smooth surface. Stainless steel can not suffer high temperature and acid electrolyte. So, this depends on your photoelectrode materials and measurement environment.
Dear Zhang Zemin,
Thank you so much for helping me out in understanding the basis of selecting a suitable substrate. It's very helpful.
Regards,
Anamika
In addition to the aforementioned reasons, FTO and ITO electrodes exhibit high overpotentials for O2 production from water and thus ensure minimal background activity.
Dear Mahmoud Elbaz,
Thank you so much for providing me the insight.
Regards,
Anamika
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