Hierarchical BiOBr, AgBr/BiOBr and BiOBr(x)I(1-x) Nano-Assembled Microspheres for Photocatalytic Methyl Orange Treatment.

We prepared hierarchical BiOBr, AgBr/BiOBr and BiOBr(x)I(1-x) (x = 0.3, 0.5 and 0.7) microspheres in ethylene glycol by a solvothermal method, then analyzed them by scanning electron microscopy, X-ray diffraction crystallography, Raman, UV-Visible absorption, BET surface area measurement and photoluminescence spectroscopy. In addition, their photocatalytic activities for methyl orange were tested under irradiation by visible light. The BET surface area, adsorption and photocatalytic activity occurred in the order AgBr/BiOBr < BiOBr << BiOBr(x)I(1-x) (x = 0.3, 0.5 and 0.7). The flower-like BiOBr microspheres exhibited a band gap of 2.76 eV, which decreased with increasing I/Br ratio. The *O2- and h+ were found to be major active species for MO degradation. For BiOBr and AgBr/BiOBr microspheres, *OH radical formation was clearly observed, while the role of *OH radical was found to be negligible for BiOBr(x)I(1-x) (x = 0.3, 0.5 and 0.7) microspheres.