First principles of Fe/Co/Ni doping and the coexistence of O vacancy in the magnetic and optical properties of rutile TiO₂(110) surface

Abstract

The research on the photocatalytic properties of TiO2 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 TiO2 have been rarely reported. Oxygen vacancies are the most common point defects in TiO2 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 TiO2(110) surface. The findings indicated that the formation energy of the (110) surface of rutile TiO2 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/VO-TiO2, Co/VO-TiO2, and Ni/VO-TiO2 systems all exhibited magnetism on the (110) surface. The Fe/VO-TiO2(110) surface had the largest magnetic moment and the best magnetic properties. The study of optical properties showed that the Fe/VO-TiO2(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-TiO2(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 O2 by dissociation of water on the surface of rutile TiO2(110).