SCHEDULED MAINTENANCE
Adsorption and UV/Visible photocatalytic performance of BiOI for methyl orange, Rhodamine B and methylene blue: Ag and Ti-loading effects†
Abstract
We synthesized echinoid-like BiOI microspheres with various doped concentrations of Ag (0.1, 1.0, 5.0, 10.0 mol%) and Ti (1.0, 5.0, 10.0, 30.0, 50.0 mol%) in ethylene glycol and then examined their fundamental properties by scanning electron microscopy, transmission electron microscopy, X-ray diffraction analysis, UV-visible absorption, FT-IR, Raman, photoluminescence and Brunauer–Emmett–Teller (BET) surface area measurements. We also measured the adsorption and photocatalytic dye-degradation performance of the catalysts using methyl orange (MO), Rhodamine B (RhB) and methylene blue (MB). The adsorption performance was found to be in the order of MO < RhB < MB, and to depend somewhat upon the Ag and Ti-loadings. MO was degraded in the order of BiOI < Ag–BiOI < Ti–BiOI under UV and visible light irradiation, while the degradation of RhB was in the order of Ag–BiOI ≈ Ti–BiOI ≪ BiOI, and Ag–BiOI < BiOI < Ti–BiOI, respectively. MB showed poor photodegradation under UV and visible light. Finally, we used an indirect chemical probe method with active species scavengers and photoluminescence spectroscopy to clarify the dye-sensitized photodegradation mechanism. In the mechanism, ˙O2− and h+ were active species under visible light irradiation. No ˙OH radicals were found by luminescence spectroscopy.
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