Highly improved photocatalytic degradation of rhodamine B over Bi2Ga4?xFexO9 solid solutions under visible light irradiation

摘要

In this work, Bi _(2) Ga _(4? x ) Fe _( x ) O _(9) (0 ≤ x ≤ 1.2) solid solutions were prepared via the traditional high-temperature solid-state reaction. The Le Bail fitting on the powder X-ray diffraction patterns shows that these solid solutions were successfully synthesized. Scanning electron microscopy showed that the Bi _(2) Ga _(3.2) Fe _(0.8) O _(9) sample was composed of sub-micron particle crystallites. Energy dispersive spectroscopy analysis and X-ray photoelectron spectroscopy were used to identify that the Fe element is trivalent when doping into the crystal structure. Ultraviolet-visible diffused reflectance spectra suggested that the bandgap of Bi _(2) Ga _(3.2) Fe _(0.8) O _(9) is narrower than that of the undoped Bi _(2) Ga _(4) O _(9) sample. Three strategies, including Fe ~(3+) doping, addition of H _(2) O _(2) , and loading of the cocatalyst, were utilized to improve the photocatalytic degradation activity. The optimum photocatalytic performance was obtained over 2.5 wt% Cu/Bi _(2) Ga _(3.2) Fe _(0.8) O _(9) sample in 20 ppm RhB aqueous solution (containing 1.5 mL H _(2) O _(2) ) under visible light irradiation. Its photodegradation rate is 8.0 times that of Bi _(2) Ga _(4) O _(9) containing 0.5 mL H _(2) O _(2) . The 2.5 wt% Cu/Bi _(2) Ga _(3.2) Fe _(0.8) O _(9) photocatalyst remained stable and active even after four cycles. Also, its photocatalytic conversion efficiency for RhB was nearly 100%, which was achieved in 3 hours. The photocatalytic mechanism indicated that ·OH and h ~(+) played an important role in the photocatalytic degradation reaction.