First-Principle Insight Into the Effects of Oxygen Vacancies on the Electronic, Photocatalytic, and Optical Properties of Monoclinic BiVO(4)(001)

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 O(2) and H(2)O and the density of states (DOS) of monoclinic bismuth vanadate (m-BiVO(4)). Ovac were stable when incorporated into m-BiVO(4)(001) and increased the adsorption energy of O(2). Ovac changed the V3d orbitals of m-BiVO(4)(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-BiVO(4) with different Ovac levels was prepared via hydrothermal synthesis. X-ray diffraction (XRD) patterns confirmed the existence of the (001) crystal surface of m-BiVO(4). In addition, X-ray photoelectron spectroscopy (XPS) and electron spin resonance (ESR) spectroscopy of m-BiVO(4) confirmed the presence of Ovac and demonstrated that, as the Ovac level increased, the number of superoxide radicals ([Formula: see text]) and hydroxyl radicals (·OH) produced increased. In addition, m-BiVO(4) with a higher Ovac level possessed superior photocatalytic properties to and degraded rhodamine B (RhB) dye nearly 2-fold faster than m-BiVO(4) 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.