Low temperature synthesis and photocatalytic properties of highly oriented ZnO/TiO_2-xN_y coupled photocatalysts

A novel photocatalysts, ZnO thin film with nanotube arrays was prepared via soft solution route without any polymer additives and subsequently using a facile chemical etching of ZnO nanorods arrays along the c-axis. The thin film of large-scale ZnO arrays could be produced directly on the glass substrates. Scanning electron microscopy, diffuse reflectance spectra and X-ray diffraction were systematically used to confirm the successful fabrication of the patterns and to characterize the structure and morphology. The possible mechanism to form the ZnO nanotube array via such a facile approach was also discussed. Moreover, nitrogen doped titania (TiO_2-xN_y) as sensitizers were coupled with the ZnO nanotube and nanotube arrays in order to give the visible-light responsiveness. The investigation of photocatalytic ability proved that the ZnO nanotube arrays/TiO_2-xN_y composites showed excellent photocatalytic activities for the decomposition of NO_x gas under both visible-light and UV light irradiation, being superior to that of ZnO nanorods, ZnO nanotube, TiO_2-xN_y, commercial TiO₂ (AEROXIDE^® P25) powders and ZnO nanorod arrays/TiO_2-xN_y composites.