Green Hydrogen Production via Water Splitting Using SrFe _0.9 Mo _0.1 O _{3− <i>δ</i>} Perovskite as a Catalyst

Evidence of hydrogen production from water splitting using a nonstoichiometric cubic perovskite, SrFeMoO (SFMO), as a catalyst under moderate operating condition is presented. It is demonstrated that the SFMO oxide, when reduced at 800 °C in air, can dissociate water to produce hydrogen and oxygen at the same temperature. The direct test of water dissociation with consequent hydrogen production is carried out using quadrupole mass spectrometry (QMS) under ultrahigh vacuum conditions, where the production of hydrogen by the material is unambiguously determined using heavy water. In addition, in operando synchrotron X‐ray diffraction and X‐ray absorption spectroscopy are employed to track structural and electronic changes during the reaction, revealing a reversible unit cell expansion without oxygen incorporation and indicating a nonredox mechanism distinct from that of conventional perovskites. This combined characterization approach enables correlation between gas‐phase evolution and the structural and electronic response of the catalyst. The reaction cycle could be repeated several times without any decomposition, segregation, or irreversible structural changes, demonstrating the high stability of SFMO. These findings highlight SFMO as a robust and stable catalyst for sustainable hydrogen generation, with strong potential for integration into solar‐driven water splitting technologies.