First principles of Fe/Co/Ni doping and the coexistence of O vacancy in the magnetic and optical properties of rutile TiO 2 (110) surface

Abstract The research on the photocatalytic properties of TiO 2 by doping transition metals (Fe/Co/Ni) has achieved certain progress. However, the effects of Fe/Co/Ni doping and the coexistence of O vacancies on the photocatalytic properties of TiO 2 have been rarely reported. Oxygen vacancies are the most common point defects in TiO 2 materials, and the precise control of O vacancies in experiments presents difficulty. To solve this problem, this study used first principles under the framework of density functional theory to investigate the effects of Fe/Co/Ni doping and the coexistence of O vacancies on the magnetic and optical properties of rutile TiO 2 (110) surface. The findings indicated that the formation energy of the (110) surface of rutile TiO 2 doped with transition metals Fe, Co, and Ni and coexisting with O vacancies was smaller under Ti-rich conditions than under O-rich conditions. Under Ti-rich conditions, the doping system easily formed and exhibited a high stability. The findings on magnetic properties indicated that the Fe/V O -TiO 2 , Co/V O -TiO 2 , and Ni/V O -TiO 2 systems all exhibited magnetism on the (110) surface. The Fe/V O -TiO 2 (110) surface had the largest magnetic moment and the best magnetic properties. The study of optical properties showed that the Fe/V O -TiO 2 (110) surface had the longest carrier lifetime, strongest surface activity, and most evident red shift in the absorption spectrum. The oxidation capability of the Fe/VO-TiO 2 (110) surface was relatively the best. Fe doping and the coexistence of O vacancies are the most beneficial to the photocatalysts for the production of O 2 by dissociation of water on the surface of rutile TiO 2 (110).