Towards spectroscopic monitoring of photoelectrodes: In-situ Raman photoelectrochemistry of a TiO2/prussian blue photoanode

Abstract

Here, novel in-situ Raman photoelectrochemical measurements are performed. The obtained results have proved that it is possible to track the progress of a photoelectrochemical reaction that takes place on a semiconducting electrode using the spectroscopic method. As an exemplary system, the Ti/TiO2/Prussian blue electrode is investigated. Since TiO2 is an n-type semiconductor, it cannot act as an efficient anode in dark conditions. Thus, once electrochemically reduced Prussian blue deposited on TiO2 is not reoxidized during anodic polarization. However, Everitt's salt oxidation may be possible when photoexcitation of TiO2 with UV LED radiation takes place at a potential which is more anodic than the flat band potential of the semiconductor. This process is successfully monitored in-situ using Raman spectroscopy. The measurements performed at different conditions allow to distinguish between processes induced by polarization and illumination (or both). The proposed method of photoelectrode characterization through a real-time monitoring approach can be further developed and utilized for other photoelectrochemical systems.