Zn–TiO2 mesoporous oxides prepared by mechanical milling

Abstract

Zn–TiO2 mesoporous oxides have been prepared by the mechanical milling of zinc acetate either with a surfactant free mesoporous titania or with the hybrid mesophase, in that case the surfactant is still present inside the pores. After calcination in a muffle furnace or by induction, the obtained materials have been characterized in details by SAXS, XRD, EDX, nitrogen adsorption-desorption, XPS and UV spectroscopy. The photocatalytic activity of the mesoporous oxides has also been tested on the photodegradation of methyl orange. The results show that the presence of surfactant favors the zinc dispersion, prevents from the formation of zincite and slows down the crystallization of anatase. The recovered materials present a mesopore arrangement with low crystallized walls. As a consequence, by comparison with the pure mesoporous titania having semi-crystalline anatase framework, their photocatalytic efficiency is decreased. By contrast, when zinc acetate is mechanically milled with the free surfactant mesoporous TiO2, agglomerated particles were observed by EDX and TEM and the zincite phase ZnO was detected by XRD. Studies of the Kubelka-Munk function revealed the presence of two band gap energies corresponding to 3.2 and 2.9 eV. The appearance of ZnO in the materials and the reduction of the band gap give a capacity for the photodegradation of methyl orange slightly higher than the one of the pure mesoporous titania with semi crystalline framework.