Water adsorption on model system perovskites: single crystal SrTiO3 for Fermi Level Engineering

The electronic structure of perovskite oxides significantly influences their catalytic performance in the oxygen evolution reaction (OER). While extensive characterization1,2 has focused on the surface properties and electronic structure of perovskite SrTiO3 interacting with water, uncertainties persist regarding modifications to enhance catalytic activity through doping, substitution, or defect engineering. The roles of the Fermi level and surface states in this process are particularly unclear. This study, part of the Collaborative Research Center 1548 FLAIR (Fermi level engineering applied to electroceramic oxides), aims to investigate the influence of adsorbed water on atomically flat single crystal SrTiO3 doped with 0.05 wt.% Nb across different crystal orientations: (100) and (110), with and without oxygen vacancies. We intend to measure changes in the electronic structure and defect states induced by water exposure by conducting near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) experiments at the BL-24-CIRCE beamline at ALBA. Techniques such as resonant photoemission spectroscopy (Res PES) and X-ray Absorption Spectroscopy (XAS) will be employed to identify orbital contributions and detect unoccupied acceptor states at the Ti L3,2-edge and O K-edge, respectively. These investigations are crucial for optimizing catalytic performance and improving materials for energy conversion and storage applications.