First-Principle Insight Into the Effects of Oxygen Vacancies on the Electronic, Photocatalytic, and Optical Properties of Monoclinic BiVO4(001)

Xiaosong Gu; Yujie Luo; Qi Li; Rui Wang; Shiqi Fu; Xiulong Lv; Qian He; Ying Zhang; Qiutong Yan; Xuan Xu; Fangying Ji; Yan Qiu

doi:10.3389/fchem.2020.601983

First-Principle Insight Into the Effects of Oxygen Vacancies on the Electronic, Photocatalytic, and Optical Properties of Monoclinic BiVO₄(001)

Front Chem. 2020 Dec 10:8:601983. doi: 10.3389/fchem.2020.601983. eCollection 2020.

Authors

Xiaosong Gu¹, Yujie Luo¹, Qi Li¹, Rui Wang², Shiqi Fu¹, Xiulong Lv¹, Qian He¹, Ying Zhang¹, Qiutong Yan¹, Xuan Xu¹, Fangying Ji¹, Yan Qiu³

Affiliations

¹ Key Laboratory of Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing, China.
² Department of Physics, Center for Quantum Materials and Devices, Institute for Structure and Function, Chongqing University, Chongqing, China.
³ School of Architectural Engineering, Yunnan Agricultural University, Kunming, China.

Abstract

In this paper, first-principle calculations were performed to investigate the effects of oxygen (O) vacancies (Ovac) on the crystal structure, electronic distribution, adsorption energies of O₂ and H₂O and the density of states (DOS) of monoclinic bismuth vanadate (m-BiVO₄). Ovac were stable when incorporated into m-BiVO₄(001) and increased the adsorption energy of O₂. Ovac changed the V3d orbitals of m-BiVO₄(001) by adding a new band gap level, causing the redundant electrons of V atoms to become carriers and promoting the separation efficiency of electrons and holes. To verify the first-principle calculations, m-BiVO₄ with different Ovac levels was prepared via hydrothermal synthesis. X-ray diffraction (XRD) patterns confirmed the existence of the (001) crystal surface of m-BiVO₄. In addition, X-ray photoelectron spectroscopy (XPS) and electron spin resonance (ESR) spectroscopy of m-BiVO₄ confirmed the presence of Ovac and demonstrated that, as the Ovac level increased, the number of superoxide radicals ( $O_{2}^{-} \cdot$ ) and hydroxyl radicals (·OH) produced increased. In addition, m-BiVO₄ with a higher Ovac level possessed superior photocatalytic properties to and degraded rhodamine B (RhB) dye nearly 2-fold faster than m-BiVO₄ with a lower Ovac level. Finally, the removal rate of RhB increased from 23 to 44%. All experimental results were in good agreement with the first-principle calculated results.

Keywords: BiVO4; first-principles method; oxygen vacancy; photocatalytic; pollutant degradation.