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

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 (O2-·) 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.

Effect of Ag-Decorated BiVO4 on Photoelectrochemical Water Splitting: An X-ray Absorption Spectroscopic Investigation

“…An energy bandgap of 2.57 eV is, therefore, obtained for both pure BiVO 4 and Ag-decorated BiVO 4 samples. This result is in agreement with a value previously reported [ 38 , 39 , 40 ]. Accordingly, loading with a small number of Ag NPs does not result in any significant change in the energy band gap of BiVO 4 .…”

“…Figure 3 b presents the Fourier-transformed amplitude of V K-edge EXAFS k 3 χ data, which show that the peak intensity increases with the concentration of decorative Ag NPs. The change in peak intensity typically arises from the variation of the coordination number of the metal center [ 39 , 40 ]. During the formation of oxygen vacancy defects, the lattice oxygen atoms escape from the structure [ 41 ], reducing the coordination number of the V atoms.…”

Optimized silicate nanozymes with atomically incorporated iron and manganese for intratumoral coordination-enhanced once-for-all catalytic therapy

“…Moreover, the hydrothermal process conferred abundant OV to FMMPG, which can narrow its bandgap to facilitate the photo-triggered charge separation and enhance the adsorption of oxygen (O 2 ) molecules and water (H 2 O) molecules on the surface of the photosensitizer, which promoted the catalytic production of ROS. 51,52 To investigate the photodynamic behavior of FMMSNs, UV-vis diffuse reflectance spectra were used to determine the band gap ( E g ) of FMMSNs, which was calculated to be 1.74 eV (Fig. 4c).…”

Surface Reconstruction and Passivation of BiVO4 Photoanodes Depending on the “Structure Breaker” Cs+

“…The strong-correlated corrections were considered by the GGA + U method with a U – J value of 2.7 eV for V 3d states. ,, Equilibrium was reached when the forces on the relaxed atoms and the energies in the self-consistent iterations became less than 0.05 eV/Å and 10 –5 eV, respectively. The van der Waals (vdW) interaction was described by the DFT-D3 method. , The monoclinic BiVO 4 structure with calculated lattice parameters of a = 5.063 Å, b = 5.285 Å, c = 11.943 Å, and the 2.41 eV band gap are consistent with the literature. − A vacuum height of 15 Å was used to eliminate the interaction between neighboring slabs. For the model construction, a p (1 × 1) BiVO 4 (110) surface with four layers was modeled, with the top two layers fully relaxed and the bottom two layers kept fixed to mimic the bulk region.…”