Highly improved photocatalytic degradation of rhodamine B over Bi(2)Ga(4−x)Fe(x)O(9) solid solutions under visible light irradiation

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.