Synergizing oxygen vacancy engineering and f-Electron doping to Promote dynamics of Rare-Earth-Doped bismuth...

Efficient exciton dissociation and surface molecular oxygen activation are crucial for advancing photocatalysis in energy and environmental applications. However, photocatalytic performance is often limited by complex electron-nuclear interactions and strong exciton binding energies, primarily due to significant exciton effects. In this work, we introduce a novel strategy to enhance exciton dissociation by doping samarium (Sm) into bismuth oxoiodide (Bi₅O₇I) to modulate the concentration of oxygen vacancies (Ov). The resulting electron-rich Ov sites activate surrounding electrons, creating localized electronic states that synergize with the strong electron-trapping potential of the 4f orbitals. This synergy facilitates a direct transition pathway for photogenerated carrier migration. The doping strategy shifts the electron transition mode from ligand-to-metal charge excitation (LMCE, p-p transition) to vacancy-to-metal charge transfer (Ov-MCT, n-p transition). This change effectively reduces the vertical excitation energy of electrons to 1.74 eV and promotes the complete spatial dissociation of excitons. Additionally, the dynamic redox cycling of samarium ions (Sm³⁺/Sm²⁺) enhances molecular oxygen activation, thereby accelerating photocatalytic oxidation reactions. These findings provide a comprehensive understanding of photocatalytic mechanisms influenced by f-electron doping and Ov engineering, offering valuable theoretical insights for the future application of rare-earth element doping in photocatalysis.