Improved visible light photocatalytic activity of MWCNT/BiOBr composite synthesized via a reactable ionic liquid

Novel flower-like MWCNT/BiOBr composite photocatalysts have been prepared through a one-pot EG-assisted solvothermal process in the presence of reactable ionic liquid 1-hexadecyl-3-methylimidazolium bromide ([C16mim]Br). The structures, morphology and photocatalytic properties of as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), Fourier transform spectrophotometer(FT-IR), diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy, photocurrent and electrochemical impedance spectroscopy (EIS). During the reactive process, ionic liquid [C16mim]Br acted as solvents, reactants, templates and MWCNT dispersing agents. The MWCNT/BiOBr composite photocatalysts exhibited a conspicuous improved photocatalytic performance for rhodamine B (RhB) degradation. The optimal MWCNT content for the photocatalytic activity was determined. The DRS analysis showed that the prepared MWCNT/BiOBr composites exhibited strong absorption ability with the increase of doped MWCNT amount. The results of PL, EIS and photocurrent analysis indicated that MWCNT could disperse and combine with BiOBr microspheres on its surface, which facilitated electron–hole separation, and contributed to improve the photocatalytic activity. The radicals trap experiments demonstrated that hole was the main reactive species during the degrading process of RhB. A possible mechanism for the enhanced photocatalytic activity of MWCNT/BiOBr was also proposed.