Three dimensional Ag2O/TiO2 type-II (p-n) nanoheterojunctions for superior photocatalytic activity.

ABSTRACT

Type-II p-n junction three-dimensional Ag(2)O/TiO(2) microspheres have been fabricated by assembling p-type Ag(2)O nanoparticle on n-type TiO(2) 3D microsphere. Ag(2)O/TiO(2) microsphere nanoheterojunctions were obtained by hydrothermal synthesis of TiO(2) microspheres at 180 °C followed by photoreduction of AgNO(3). 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 Ag(2)O/TiO(2) significantly enhanced the photocatalytic degradation compared to n-type TiO(2) microsphere. It was found that the photocatalytic degradation followed the pseudo first-order reaction model. In particular, heterostructure with molar ratio of TiO(2) and AgNO(3) of 41 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.