Investigation of the photocorrosion of GaP, III-V photoanode in acid with in situ UV/vis spectroscopy

Although III-V semiconductors are one of the most promising group of materials for high efficiency solar fuels applications, they are prone to self-corrosion in strongly acidic or alkaline solutions. In-situ Investigation of photo-corrosion process are now limited to very expensive and complicated methods that are not available in every lab. Developing methods that enable researchers to do in-situ study of photo-corrosion process could make a profound impact on this field. Herein we studied self-corrosion of GaP photoelectrodes, a promising III-V material for tandem top subcells, in acidic electrolyte via in-situ UV-Vis spectroscopy. In-situ measurement of concentration of dissolved Ga and P species that come off from the electrode to electrolyte , calculation of corrosion faradaic efficiency as a function of applied bias and time along with SEM and XPS characterization are utilized to expound the photo-corrosion process of n-GaP and p+-GaP photoelectrodes which have shown different corrosion behavior. In addition, TiO₂ protective layer was deposited on some samples to study the change in corrosion faradaic efficiency as a function of deposition parameters.