Ionic liquid-assisted synthesis of porous BiOBr microspheres with enhanced visible light photocatalytic performance

Porous BiOBr microspheres have been successfully synthesized through an ethylene glycol-assisted solvothermal method using reactive ionic liquids as templates and reactants during the synthetic process. The obtained samples were characterized using X-ray diffraction, scanning and transmission electron microscopies and X-ray photoelectron, energy-dispersive X-ray, Fourier transform infrared, diffuse reflectance and photoluminescence spectroscopies. The photocatalytic activities were evaluated using the degradation of rhodamine B and tetracycline under visible light irradiation. The photocatalytic efficiency of BiOBr photocatalyst synthesized using single-molecule ionic liquid as template is better than that of BiOBr obtained using polyionic liquid as template. A possible photocatalytic mechanism is also provisionally proposed. And the degradation rate using BiOBr-IL-1 was 2.74, 1.24 and 4.84 times higher than that using BiOBr-IL-2, BiOBr-IL-3 and BiOBr-KBr. The larger surface area and narrower energy band gap of BiOBr-IL-1 could improve the visible light harvesting ability and facilitate the separation of photogenerated electron-hole pairs and the photocatalysis process. This study affords a facile way to develop such novel photocatalysts with special morphology using ionic liquids.