Hydrothermal synthesis of star-shaped Bi5O7Br catalysts with strong visible light catalytic performance

Micron star-shaped Bi5O7Br catalysts were synthesized, with Bi(NO3)3·5H2O and cetyltrimethylammonium bromide (CTAB) as raw materials, by using a simple hydrothermal method. X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and UV–visible diffuse reflectance spectroscopy (UV–vis DRS) were used to characterize the samples. It was found that tetragonal star-shaped Bi5O7Br crystals with high crystallinity could be obtained as pH value of the solution was about 9. Compared with flaky BiOBr particles, the star-shaped Bi5O7Br sample displayed red-shift in the UV–visible absorption edge, whereas the band gap was reduced to 2.57 eV and the specific surface area was increased. Among all samples, the star-shaped Bi5O7Br had the highest photocatalytic efficiency. After visible light irradiation for 10 min, the degradation rate of the rhodamine B (RhB) solution with a concentration of 10 mg·L−1 was almost 100%. Also, its photocatalytic activity was nearly unchanged after five cycles. It is believed that such Bi5O7Br could be used as stable and effective visible light catalysts.