Preparation, Structural, and Photocatalytic Properties of Boron-Doped Bismuth Oxybromide Nanoplatelets Combined with a First-Principle Study

In this work, we propose a modified sol–gel route to obtain boron-doped BiOBr nanoplatelets and investigate its photocatalytic performance. The prepared materials were studied by X-ray diffraction (XRD), transmission electron microscopy (TEM), ultraviolet-visible diffuse reflectance spectroscopy (UV–Vis DRS), Raman spectroscopy, nitrogen adsorption–desorption measurements, X-ray photoelectron spectroscopy (XPS), steady-state photoluminescence emission, and time-resolved fluorescence decay spectra, respectively. In addition, the photocatalytic activity of the prepared samples was evaluated using model pollutants (Orange G, Rhodamine B dye and ciprofloxacin (CIP)) under simulated visible light irradiation (λ > 440 nm). The photo-degradation ratio of Orange G (OG), Rhodamine B (RhB) and CIP was ~91.0–96.0% after only 110, 180, and 60 min photocatalytic reaction by using B-doped BiOBr as catalyst, revealing that it had an excellent visible-light photocatalytic activity. In the tenth recycle, the degradation ratio of B‑doped BiOBr for CIP decomposition still reached to 80.0%. The outstanding photocatalytic activity was mainly contributed to the slowing down of recombination of electron–hole pairs. A first principle calculation on the electron band structures and density of states was also presented. The calculated band–gap ( E g ) of B‑BiOBr (2.13 eV) was smaller than that of the neat BiOBr (2.77 eV), which are compared with the experimental values; E g for B-BiOBr and neat BiOBr are 2.80 and 2.29 eV, respectively. The results of first principles calculations indicating B doping can decrease the band–gap energy of BiOBr effectively and improve its practical visible-light energy utilization. These conclusions are consistent with experimental results.