The Electronic Structures and Optical Properties of Alkaline-Earth Metals Doped Anatase TiO2: A Comparative Study of Screened Hybrid Functional and Generalized Gradient Approximation
Jin-Gang Ma,
Cai-Rong Zhang,
Ji-Jun Gong,
You-Zhi Wu,
Sheng-Zhong Kou,
Hua Yang,
Yu-Hong Chen,
Zi-Jiang Liu,
Hong-Shan Chen
Affiliations
Jin-Gang Ma
School of Sciences, Lanzhou University of Technology, Lanzhou 730050, China
Cai-Rong Zhang
School of Sciences, Lanzhou University of Technology, Lanzhou 730050, China
Ji-Jun Gong
School of Sciences, Lanzhou University of Technology, Lanzhou 730050, China
You-Zhi Wu
State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Lanzhou University of Technology, Lanzhou 730050, China
Sheng-Zhong Kou
State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Lanzhou University of Technology, Lanzhou 730050, China
Hua Yang
School of Sciences, Lanzhou University of Technology, Lanzhou 730050, China
Yu-Hong Chen
School of Sciences, Lanzhou University of Technology, Lanzhou 730050, China
Zi-Jiang Liu
Department of Physics, Lanzhou City University, Lanzhou 730070, China
Hong-Shan Chen
College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070, China
Alkaline-earth metallic dopant can improve the performance of anatase TiO2 in photocatalysis and solar cells. Aiming to understand doping mechanisms, the dopant formation energies, electronic structures, and optical properties for Be, Mg, Ca, Sr, and Ba doped anatase TiO2 are investigated by using density functional theory calculations with the HSE06 and PBE functionals. By combining our results with those of previous studies, the HSE06 functional provides a better description of electronic structures. The calculated formation energies indicate that the substitution of a lattice Ti with an AEM atom is energetically favorable under O-rich growth conditions. The electronic structures suggest that, AEM dopants shift the valence bands (VBs) to higher energy, and the dopant-state energies for the cases of Ca, Sr, and Ba are quite higher than Fermi levels, while the Be and Mg dopants result into the spin polarized gap states near the top of VBs. The components of VBs and dopant-states support that the AEM dopants are active in inter-band transitions with lower energy excitations. As to optical properties, Ca/Sr/Ba are more effective than Be/Mg to enhance absorbance in visible region, but the Be/Mg are superior to Ca/Sr/Ba for the absorbance improvement in near-IR region.