Effect of light on the wettability properties of films made by the assembly of SiO₂ and α − Fe₂O₃ nanoparticles

Photocatalytic Degradation of Methylene Blue by Magnetic Opal/Fe3O4 Colloidal Crystals under Visible Light Irradiation

“…According to Beer's law, the MB peak in the chromatograms decreased its area as the irradiation time increased [40]. Only diminished peak intensity was observed in all The E g values obtained for SiO 2 opal and Fe 3 O 4 samples were 3.8 and 2.1 eV, which agree with previously reported values [24,36]. Considering that materials of E g higher than 3.09 require UV light to be excited, the SiO 2 opal could not act as a photocatalyst under visible light.…”

“…The surface OH groups were silanols of the SiO 2 domains (Si-OH). MB, as cations, could be easily absorbed by the negatively charged surface of the SiO 2 spheres [36,54,55]. That adsorption mechanism has been reported by Zhang et al [39] and is illustrated in reactions (2) and (3):…”