Hydrothermal synthesis of Ag2O/Bi2O3 microspheres for efficient photocatalytic degradation of Rhodamine B under visible light irradiation

Ag2O/Bi2O3 microspheres were successfully synthesized by a facile co-precipitation hydrothermal method in the presence of surfactant polyvinylpyrrolidone (PVP). X-ray diffraction confirmed that Ag2O/Bi2O3 was made up of the cubic Ag2O phase and the tetragonal Bi2O3 phase. Scanning electron microscopy and transmission electron microscopy showed that the synthesized Ag2O/Bi2O3 microspheres were assembled by radially grown nanosheets with the thickness of about 50 nm. In comparison with N-doped TiO2, Bi2O3 and Ag2O, the Ag2O/Bi2O3 composites showed much higher efficiency for photodegradation of Rhodamine B (RhB) under visible light irradiation (λ≥420 nm). Among the Ag2O/Bi2O3 composites, the sample with 0.3 mol fraction of Ag2O exhibited the highest photocatalytic activity. The excellent photocatalytic activity of Ag2O/Bi2O3 may be ascribed to the strong visible light absorption resulting from the quantum dot sensitization of Ag2O and the efficient separation of photogenerated electron–hole pairs through Ag2O/Bi2O3 heterojunction. The possible photocatalytic mechanism was proposed based on band gap structure analysis and the reaction effects by adding the radical scavengers.