La0.2Sr0.25Ca0.45TiO3 Surface Reactivity with H2: A Combined Operando NEXAFS and Computational Study

A-site doped SrTiO₃ is considered as a promising substitute for traditional anodic metals in solid oxide fuel cells (SOFCs). In this study, we present the reactivity of La_0.2Sr_0.25Ca_0.45TiO₃ (LCSTO), La_0.2Sr_0.7TiO₃ (LSTO), and SrTiO₃ (STO) toward H₂ by operando ambient pressure NEXAFS spectroscopy and theoretical spectra simulation with FDMNES code. The samples were synthesized by MBE (molecular beam epitaxy), hydrothermal, and modified-Pechini routes. We found that the reducibility of the samples depends not only on their stoichiometry but also on the morphology, which is determined by the synthetic method. The results of these experiments give insight into the reducibility of Ti⁴⁺ in perovskites as well as the opportunity to further optimize the synthesis of these materials to obtain the best performance for SOFC applications.