Due to their promising photovoltaic performances, III-V photoabsorbers such as InP gain a lot of attraction with respect to their application in the field of photoelectrochemical water splitting . However, the role of surface defects, especially in contact with the liquid electrolyte, is still not fully understood, impeding further efficiency improvement of the photoelectrode. For that reason, the focus was redirected to the electrochemical interface of the semiconducting photoabsorber and the liquid electrolyte in the last decade . Furthermore, the interaction of InP as photoabsorber with water is also of high relevance when depositing conductive oxides as electrochemical buffer layer using atom layer deposition (ALD) where water frequently is used as oxide precursor .