Facile construction of BiOBr ultra-thin nano-roundels for dramatically enhancing photocatalytic activity.

BiOBr is a kind of promising photocatalyst because of excellent photoelectric separation efficiency and chemical stability. In order to improving practical application performance, a novel BiOBr ultra-thin nano-roundel (BiOBr-nR) was constructed in water-in-oil (WIO) emulsion microspheres, and prepared by hydrothermal reaction. Its specific surface area was increased by changing microtopography and downsizing. After being characterized by FT-IR, X-ray photoelectron spectroscopy (XPS), powder X-ray diffraction (XRD), scanning electron microscope (SEM), Brunauer-Emmett-Teller (BET), UV-Vis diffuse reflectance spectra (UV-Vis DRS) and photoluminescence (PL), it indicated the BiOBr-nR, being doped by C and N, is 4-5 times smaller and thinner than that of conventional BiOBr. It was also found that BiOBr-nR has narrower band gap energy (2.78 eV), excellent photocatalytic activity, significant reusability, and stability. The obtained BiOBr-nR photocatalysts were applied to remove organics. It presented excellent photocatalytic activity, the degradation rate of organics got to 99.2%. The mechanism of photodegradation was investigated, which indicated superoxide radicals and holes play a major role in the degradation of organics. Therefore, BiOBr-nR is a kind of environmentally friendly photocatalyst with stable photocatalytic activity, the removal rate still more than 97% after recycling for 10 times. In summary, we found a novel insight for designing and preparation of efficient and recyclable BiOBr photocatalytic materials, which exhibits high photoresponse for purifying the wastewater.