Fabrication of Ag2O/TiO2 with enhanced photocatalytic performances for dye pollutants degradation by a pH-induced method

Abstract Ag2O/TiO2 composites synthesized in this study were applied into the photocatalytic degradation of methyl orange (MO) under UV and visible light irradiation. X-ray diffraction, X-ray photoelectron spectroscopy and transmission electron microscope analysis demonstrated that Ag2O nanoparticles were well distributed on the surface of TiO2 and the heterostructure of Ag2O/TiO2 was formed. Compared with the pure TiO2 and Ag2O, the 3% and 50% Ag2O/TiO2 composite displayed much higher photocatalytic activities in MO degradation under UV and visible light irradiation, respectively. The degradation rate constant of 50% composite was 0.01508 min−1 under visible light, which was almost 20.1 and 1.2 times more than that of the pure TiO2 and Ag2O, respectively. Moreover, the formation of Ag(0) on the surface of Ag2O under illumination contributed to the high stability of Ag2O/TiO2 photocatalysts. It was also found that hydroxyl radicals during the photocatalytic process played the predominant role in MO degradation. The enhanced photochemical activities were attributed to the formation of the heterostructure between Ag2O and TiO2, the strong visible light absorption and the high separation efficiency of photogenerated electron–hole pairs resulted from the highly dispersed Ag2O particles.