Three Dimensional Ag2O/TiO2 Type-II (p-n) Nanoheterojunctions for Superior Photocatalytic Activity

Type-II p-n junction three-dimensional Ag2O/TiO2 microspheres have been fabricated by assembling p-type nanoparticle on n-type TiO2 3D microsphere. Ag2O/TiO2 microsphere nanoheterojunctions were obtained by hydrothermal synthesis of TiO2 microspheres at 180 degrees C followed by photoreduction of AgNO3. The samples were carefully characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), field-emission scanning electron microscopy (FESEM), and energy dispersive X-ray analysis (EDX). The photocatalytic activity toward degradation of methyl orange (MO) aqueous solution under UV light was investigated. The result showed that type-II p-n nanoheterojunctions Ag2O/TiO2 significantly enhanced the photocatalytic degradation compared to n-type TiO2 microsphere. It was found that the photocatalytic degradation followed the pseudo first-order reaction model. In particular, heterostructure with molar ratio of TiO2 and AgNO3 of 4:1 exhibited best photocatalytic activity and the corresponding apparent first-order rate constant of 0.138 min(-1) which is 4 times than that of pure n-type microsphere.