One-pot synthesis of bismuth oxyhalide/oxygen-rich bismuth oxyhalide heterojunction and its photocatalytic activity

BiOBr/Bi24O31Br10 heterojunction photocatalysts were prepared by a facile solvothermal method for the first time. The X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), N2 sorption, UV-vis diffuse reflectance spectroscopy (UV-vis DRS) and photoluminescence (PL) were applied to investigate the structures, morphologies, surface areas and photocatalytic properties of as-prepared samples. The photocatalytic activity of the samples was evaluated by the photocatalytic degradation of Rhodamine B under the visible-light irradiation. The results showed that BiOBr/Bi24O31Br10 heterojunctions with the different Bi24O31Br10 contents could be obtained by simply adjusting the amount of NaOH solution, all of which exhibited enhanced photocatalytic activity compared with bare BiOBr or Bi24O31Br10. Among them, the BiOBr/Bi24O31Br10 heterojunction prepared with 1.5ml of NaOH solution possessed the highest photocatalytic activity. The photogenerated holes and ·O2(-) radicals were confirmed to be the main active species responsible for the photodegradation of RhB. The mechanism of enhanced photocatalytic activity was discussed and the transfer process of the photogenerated charges carrier between BiOBr and Bi24O31Br10 was proposed on the basis of the estimated energy band positions.