Interface Engineering and Oxygen Vacancy Control in SrTiO ₃ ‐TiO ₂ Eutectics

Abstract The development of highly efficient semiconducting materials is essential for achieving the high‐yield and stable hydrogen and/or oxygen evolution reactions (HER/OER) in photoelectrochemical (PEC) water splitting reactions. The SrTiO ₃ ‐TiO ₂ eutectic compound has recently emerged as a perspective material with extraordinary activities in the PEC field due to the unique crystallographic and electronic properties caused by the large number of oxygen vacancies in the bulk. In the present study, different experimental techniques (XPS, SEM/EDX, TEM/EDX) are used to provide a detailed investigation of the changes in the structural and electronic properties of the SrTiO ₃ ‐TiO ₂ eutectic upon annealing under various gaseous environments (in vacuum, air, oxygen, argon). These results demonstrate that thermal annealing in different environments significantly enhances the formation of a sharp interface between the two crystalline phases and allows to control the concentration of the oxygen vacancies within the eutectic material.