Preparation and characterization of SnO nanoflowers with controllable thicknesses using imidazolium-based ionic liquids as green media: Visible light photocatalytic degradation of Acid Blue 19

Abstract

SnO nanoflowers with controllable thicknesses were prepared using a nonhydrothermal approach in mild conditions. Imidazolium-based ionic liquids, ILs, containing 1-butyl-3-methylimidazolium bromide, 1-hexyl-3-methylimidazolium bromide, and 1-octyl-3-methylimidazolium bromide, were applied during the preparation process as proper templates. The SnO nanoflowers with high purity and quality were prepared using 1:4:4 M ratios of SnCl2/NaOH/IL using simple reflux method at ambient pressure. The samples were analyzed by IR, XRD, SEM, EDX and DRS methods. The FT-IR spectrum obtained during the analysis confirmed the preparation of pure SnO. It should be noted that none of the ionic liquid functional groups were present in the samples and ILs only served as templates. Also, X-ray diffraction (XRD) and scanning electron microscopy (SEM) confirmed high crystalline levels of as synthesized Romarchite SnO nanoparticles with thicknesses ranging from 48 to 88 nm. Furthermore, EDX analysis showed no traces of SnCl2 and IL in the sample which indicated high purity. The results indicated that the alkyl moiety variations of the ionic liquids affected the nanoflower sizes; therefore, reducing the alkyl chain length caused a decrease in the thicknesses of the SnO nanosheets. The results, moreover, illustrated that using diverse ionic liquids not only produced nanosheets with different thicknesses but also had a direct effect on the band gaps of the sheets. The UV–Vis diffuse reflectance spectrum of S1 (SnO nanosheets prepared in [bmim][Br]) with minimum thickness, has a band gap of 2.6 eV. Photodegradation in the aqueous solution showed 94.39% by the first-order kinetic model for Fast Acid Blue R (Acid Blue 19) by S1.