Microwave-Assisted Synthesis of BiOBr Microspheres for Photocatalytic Degradation of Tartaric Acids in Aqueous Solution

A facile one-pot microwave assisted solvothermal synthesis using various ratios of ethylene glycol (EG) and ethanol was developed to synthesize flower-like BiOBr microspheres. Such synthesized microspheres were characterized using X-ray photoelectron spectroscopy, X-ray diffraction, field emission scanning electron microscopy, high resolution transmission electron microscopy, the Brunauer-Emmett-Teller surface area, and UV-Visible diffuse reflectance spectra. Flower-like BiOBr microspheres were composed of loosely packed nanoplates which are interconnected to each other. Experimental results suggested that ethanol played a crucial role in directing the construction of microspheres without any misorientations. The photocatalytic activity of BiOBr microspheres was tested using the photodegradation of tartaric acid irradiated with visible light and compared with solvothermally synthesized BiOBr microspheres and commercial Bi2O3. BiOBr microspheres synthesized using the solvent mixture containing EG and ethanol at the ratio of 3:1 could degrade 98 % tartaric acid in 240 min with visible light (lambda >= 400 nm) due to the synergistic effect of favorable microstructure with high surface area and suitable band gap of 2.92 eV. Since the resulting BiOBr microspheres are reusable without any loss in photocatalytic activity and more stable without any change in their morphology, it holds as a very promising photocatalysts for the treatment of organic pollutants.