Weak Field Tuning of Transition-Metal Dopant Hybridization in Solid Hosts

Abstract

Transition-metal (TM)-doped solids are one of the most extensively studied compounds in the fields of catalysis, magnetism, solar cells, etc., due to their tunable optoelectronic properties that stem from TM energy-level hybridization. In this work, the hybridization of the Ni–O bond in TiO2:Ni films was controlled in a stable, reversible manner via surface functionalization with polarized molecules. The Ni-doped TiO2 surface was functionalized with para-benzoic acid groups to modify the electron density distribution within the film. The dopant distribution and elemental composition at the interface are probed via high-resolution transmission electron microscopy coupled with electron energy loss spectroscopy mapping. The effect of the surface modification on the dopant, Ni2+, is studied via surface-sensitive electronic characterization techniques, such as X-ray photoelectron spectroscopy and soft X-ray absorption spectroscopy (XAS). The electron density in the valence orbitals of the dopant was observed t...