Efficient removal of organic contaminants by a visible light driven photocatalyst Sr6Bi2O9

Sr6Bi2O9 powders were synthesized by a sol–gel method using Bi(NO3)3·5H2O and Sr(NO3)2 as the starting materials and were characterized by X-ray diffraction (XRD), UV–vis diffuse reflectance spectrum (UV–vis DRS), Fourier transform infrared (FT-IR) spectrum and Raman spectrum. The as-prepared Sr6Bi2O9 powders showed an efficient photocatalytic activity in the decomposition of 4BS dye (a widely used azo dye) and 4-nitrophenol (4-NP, a priority pollutant) under visible light irradiation (λ > 400 nm). TA-PL analysis reveals that HO was not the dominant photooxidant. The radical scavengers experiments indicated that the main active species was O2− in the photocatalytic degradation of dye under visible irradiation. A possible photodegradation mechanism of organic pollutants by the visible light driven Sr6Bi2O9 was discussed.