The Electronic Structures and Optical Properties of Alkaline-Earth Metals Doped Anatase TiO2: A Comparative Study of Screened Hybrid Functional and Generalized Gradient Approximation

Materials

Jin-Gang Ma²  Cai-Rong Zhang²  Ji-Jun Gong²  You-Zhi Wu³  Sheng-Zhong Kou³  Hua Yang²  Yu-Hong Chen²  Zi-Jiang Liu⁴  Hong-Shan Chen¹ 

[1] College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070, China; E-Mail:;School of Sciences, Lanzhou University of Technology, Lanzhou 730050, China; E-Mails:;State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Lanzhou University of Technology, Lanzhou 730050, China; E-Mails:;Department of Physics, Lanzhou City University, Lanzhou 730070, China; E-Mail:

关键词: alkaline-earth metal;    anatase TiO₂;    doping mechanism;    electronic structures;    density functional theory;   

DOI  :  10.3390/ma8085257

来源: mdpi

【 摘 要 】

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.

【 授权许可】

CC BY   
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