Increased Hydrogen Production of Perovskite Solar Thermochemical Water Splitters by Joint Reduction on A and B Sites

Oxide based solar-thermochemical hydrogen (STCH) production operates by cyclic creation of oxygen vacancies that then react with steam to produce hydrogen. STCH performance is strongly dependent on both the change in vacancy stoichiometry (��) during cycling (����) and the output gas ratio of H₂/H₂O. Perovskites (ABO₃) have been investigated by controlled synthesis and X-ray adsorption spectroscopy (XAS) as STCH oxides in-part due to their tunable cation-dependent oxygen vacancy enthalpies. Classically, only one site, either A or B, has been responsible for charge compensation of oxygen vacancies. However, in this work we investigate water splitting by computationally designed perovskites expected to possess dual reduction on both A and B sites, which is predicted to increase vacancy formation, and hence performance, through increased formation entropy of vacancies. In-operando X-ray absorption spectroscopy (XAS) results at Ce L-edge and Mn and V K- and L-edges will demonstrate changing oxidation states of A and B site elements. Additional in-operando diffraction and mass loss experiments will correlate ���� and structural changes with cation reduction. This work will demonstrate the effectiveness of dual site reduction as a design criterion for STCH material design.