Enhanced Photo-Fenton Activity of SnO/α-FeO Composites Prepared by a Two-Step Solvothermal Method.

The x-SnO/α-FeO (x = 0.04, 0.07, and 0.1) heterogeneous composites were successfully prepared via a two-step solvothermal method. These composites were systematically characterized by the X-ray diffraction technique, field emission scanning electron microscopy, an energy dispersive spectrometer, X-ray photoelectron spectroscopy and a UV-visible spectrometer. It was found that SnO nanoparticles were uniformly decorated on the surface of α-FeO particles in these heterogeneous composites. A comparative study of methylene blue (MB) photodegradation by α-FeO and x-SnO/α-FeO composites was carried out. All x-SnO/α-FeO composites showed higher MB photodegradation efficiency than α-FeO. When x = 0.07, the MB photodegradation efficiency can reach 97% in 60 min. Meanwhile, the first-order kinetic studies demonstrated that the optimal rate constant of 0.07-SnO/α-FeO composite was 0.0537 min, while that of pure α-FeO was only 0.0191 min. The catalytic mechanism of MB photodegradation by SnO/α-FeO was examined. The SnO can act as a sink and help the effective transfer of photo-generated electrons for decomposing hydrogen peroxide (HO) into active radicals. This work can provide a new insight into the catalytic mechanism of the photo-Fenton process.