Theoretical insights on the exsolved behavior of ruthenium atom in titanate perovskite

Understanding the formation of active nanoparticles at the surface of perovskite oxide supports is vital to improving the electrochemical properties of catalysts. Surface-modified titanates via exsolution have shown great potential applications in energy conversion and storage devices. However, the details of exsolution are unclear, especially at the atomic level. In this work, we use the framework of density-functional theory (DFT) to investigate the exsolved mechanism of Ru atoms on novel SrTiO3-based perovskite, Sr0.975Y0.125Ti0.95Ru0.05O3-delta (SYTR). It is found that the segregation energy of Ru from bulk to surface turns from positive to negative by partially substituting A-site strontium with yttrium. The formation of oxygen vacancy accelerates the dynamic process of exsolution. Ru nanoparticles nucleate preferentially around the vicinity of yttrium sites based on the analysis of the transition states of Ru adatoms. A lower activation energy migration path of Ru could be obtained due to the introduction of A-site deficiency and surface oxygen vacancies simultaneously. The results demonstrate in this work provide significant insights to understand the mechanism of exsolution behavior in titanate perovskites.

Automated summary

Understanding the mechanism of active nanoparticle formation at the surface of perovskite oxide supports is crucial for enhancing the electrochemical properties of catalysts. Through density-functional theory and experimental studies, researchers have discovered that altering the perovskite structure, such as partial substitution and oxygen vacancy introduction, can facilitate the exsolution process of Ru atoms on the surface. These findings provide valuable insights for further optimization of the electrochemical performance of catalysts.