Controllable synthesis of uniform BiOF nanosheets and their improved photocatalytic activity by an exposed high-energy (002) facet and internal electric field

Abstract

To date, it still remains a big challenge to develop a new photocatalyst for photocatalysis technology. Herein, the BiOF photocatalyst with a regular nanosheet shape have been, for the first time, prepared by a simple hydrothermal method. The samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), ultraviolet-visible diffuse reflectance spectrum (UV-DRS), electrochemistry impede spectrum (EIS) and nitrogen sorption isotherms. Also, the Ab initio density functional theory (DFT) calculations have been carried out to give an insight into the energy * Corresponding author. Tel./2 band and electronic structures of BiOF. Further, rhodamine B (RhB) is chosen as the representative dye pollutant to evaluate the photocatalytic activity of BiOF. The results show that the uniform BiOF nanosheets grow preferentially along the [110] and [100] orientation, and 75.4% of (002) facets are exposed. After 60-min ultraviolet light irradiation (< 420 nm), 79.3% of RhB is degraded by BiOF, while only 33.7% of RhB is degraded by commercial rutile TiO 2 . The apparent kinetic rate constant (0.02534 min −1 ) over BiOF is 3.88 times as high as that (0.00652 min −1 ) over rutile TiO 2 . Moreover, the calculation results demonstrate that the high-energy (002) facets are more active than the low-energy (020) and (200) facets. For the layered BiOF, there is an internal electric field (IEF) perpendicular to the [Bi 2 O 2 ] 2+ slabs and fluorine anionic slabs, favors for the efficient separation of photogenerated electrons and holes. It is the synergetic effect of surface structure and bulk IEF that greatly improve the activity of BiOF nanosheets. We expect that bulk IEF adjustment is another new strategy to develop new, efficient photocatalyst for the layered materials.

Internal Polarization Modulation in Bi2MoO6 for Photocatalytic Performance Enhancement under Visible‐Light Illumination

“…Recently, the introduction of a built‐in electric field inside polar photocatalysts proved effective for the improvement of their photocatalytic performances because the internal electric field could provide the driving force for electrons and holes to move in opposite directions for enhanced separation . Most research in polar photocatalysts is now focused on exploring polar semiconductors as novel photocatalysts, including GaN, ZnO, BaTiO 3 , NaNbO 3 , Sr 2 (Ta,Nb) 2 O 7 , Cu 2 (OH)PO 4 , BiOCl, BiOF, BiOIO 3 , Na 3 VO 2 B 6 O 11 , and Bi 7 Fe 3 Ti 3 O 21 , whereas fewer efforts have been made on the modulation of their internal polarization through the precise control of their structure to modulate their photocatalytic performances.…”

Facet, Junction and Electric Field Engineering of Bismuth‐Based Materials for Photocatalysis

“…In this process, the photoexcited electrons have a decreased loss because of the short diffusion distance, which caused a higher charge injection value. Other photocatalysts, for example Bi 4 O 5 I 2 , BiOF, Bi 2 WO 6 , have been also been reported to have an IEF for improving charge separation.…”

Enhancing Charge Separation in Photocatalysts with Internal Polar Electric Fields

“…Under the effect of those two internal electric fields on charge separation and transfer, the BiOI(001)/BiOCl(010) heterostructure exhibited optimal activity compared to those with only one internal electric field . Additional systems, for example Bi 4 O 5 I 2 , BiO 1.18 I 0.64 , Bi 2 MoO 6 , x BiOBr‐(1− x )BiOI, and BiOF, have been reported to have an internal electric field promoting charge separation.…”