Preparation and photocatalytic performance of the Mn/BiOCl albizia flower

Abstract

Different molar ratio manganese-doped BiOCl composites (Mn/BiClO) were prepared by the hydrothermal method with imidazole hydrochloride [HMIM]Cl as the chlorine source and template. The Mn/BiClO composites were analyzed by X-ray diffraction (XRD) for crystalline structure, scanning electron micrography (SEM) for morphology, energy dispersive spectroscopy for element analysis, BET for the specific surface area and pore volume of the sample, diffuse reflectance spectra for optical properties, and X-ray photoemission spectroscopy (XPS) for the composition and the valence of the ions on the surface layer of the sample. The XRD analysis indicates that there is an increase in the peak intensity of Mn/BiOCl. The ultraviolet–visible measure result shows that the optical absorption edge appears to red-shift, which demonstrates the band gap of BiClO reduction by doping with Mn. The BiClO microflower completely spread in a hexapetalous manner in the ionic liquid (IL), increasing the chance of contact between catalyst and dye. The 23.5 % Mn/BiClO completely spread resembling an albizia flower. SEM and BET show that the Mn/BiClO albizia flower possessed greater surface area than the hexapetalous BiClO. XPS proves that Mn, Cl, O, and Bi are all present in Mn/BiOCl. These results show that doping with Mn not only improves ultraviolet photocatalytic activity, but also enhances visible photocatalystic performance of BiClO in the degradation of rhodamine. The results can be attributed to the prolongation of the lifetime of photogenerating electron–hole pairs, increase of surface area, and enlargement of optical absorption range by doping with Mn. Mn/BiClO completely degrades rhodamine B in just 40 min under ultraviolet light; moreover, Mn/BiClO can degrade 72 % of rhodamine B within 120 min under visible light. The photocatalyst experiment can be implemented in conditions of ice and water without adding any other chemical agent such as H2O2. This highly effective catalyst that can make full use of the sunlight has been seldom reported and demonstrated in the current literature.