Oxygen-Vacancy-Driven Orbital Reconstruction at the Surface of TiO<sub>2</sub> Core-Shell Nanostructures.
basic_science · Level V
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- Record sourced from PubMed, PMID 34585926.
- Also identified by DOI 10.1021/acs.nanolett.1c01995.
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Abstract
Oxygen vacancies and their correlation with the electronic structure are crucial to understanding the functionality of TiO<sub>2</sub> nanocrystals in material design applications. Here, we report spectroscopic investigations of the electronic structure of anatase TiO<sub>2</sub> nanocrystals by employing hard and soft X-ray absorption spectroscopy measurements along with the corresponding model calculations. We show that the oxygen vacancies significantly transform the Ti local symmetry by modulating the covalency of titanium-oxygen bonds. Our results suggest that the altered Ti local symmetry is similar to the <i>C</i><sub>3<i>v</i></sub>, which implies that the Ti exists in two local symmetries (<i>D</i><sub>2<i>d</i></sub> and <i>C</i><sub>3<i>v</i></sub>) at the surface. The findings also indicate that the Ti distortion is a short-range order effect and presumably confined up to the second nearest neighbors. Such distortions modulate the electronic structure and provide a promising approach to structural design of the TiO<sub>2</sub> nanocrystals.