Photodegradation Attenuated Oscillation:A Novel Photocatalytic Characteristic for the Polymetallic Oxide Semiconductor Porous Materials with Energy Bandgap Gradient

Abstract

AbstractSamples of metal oxide SnO2 and its composite SnO2/Bi2O3, ploymetallic oxides SnO2/Bi2O3/CdO, SnO2/Bi2O3/Fe2O3, and SnO2/Bi2O3/CdO/Fe2O3 powder materials were successfully prepared by a simple solid‐state reaction method at room temperature using sodium benzenesulfonate (SBS) surfactant as template. The synthesized powder materials were characterized by X‐ray diffraction (XRD), UV‐vis diffuse reflectance spectrum (UV‐Vis), scanning electron microscopy/energy dispersive X‐ray (SEM/EDX), infrared spectroscopy (IR), X‐ray photoelectron spectroscopy (XPS), N2 adsorption‐desorption and the migration rate testing of charges. Moreover, the adsorption characteristic and photodegradation performance of methyl blue (MB, co=100 mg/L) on the materials were investigated. The results show that the degradation rate (94.2 %) of MB on the SnO2/Bi2O3/CdO/Fe2O3 nanomaterial is the highest than that of the other materials within 10 min under the visible‐light irradiation. After that, the photodegradation rate of MB on the as‐prepared SnO2/Bi2O3/CdO, SnO2/Bi2O3/Fe2O3 and SnO2/Bi2O3/CdO/Fe2O3 semiconductor materials with energy band gap gradient generates the novel phenomena of photo‐ degradation attenuated oscillation but absent for the SnO2/Bi2O3 and SnO2 materials. It may be originated from the presence of the phase‐transitions of α‐Bi2O3 and β‐Bi2O3, the change ratio of Fe3+ and Fe2+ in the photocatalytic process, and the characteristic adsorption of MB molecular groups by the different metal oxides. This provides new ideas for future inspiring continued research on this emerging class of mixed metal oxides semiconductors and thereby enables innovations.