Preparation and photocatalytic activity of hierarchically mesoporous-macroporous TiO2-xNx

Hierarchically mesoporous-macroporous N-doped titania materials were fabricated by the thermal treatment of spontaneously formed hierarchical mesoporous-macroporous titanias with urea solution, in order to extend their photocatalytic applications froth ultraviolet to visible-light range. The resultant meso-inacroporous TiO2-xNx exhibited a bicrystalline (anatase and brookite) framework with high surface area and large porosity. The content of the doped nitrogen increased with the urea solution and the nitridation temperature, and the band gaps narrowed froth 3.14 to 2.48 eV. The formation of O-Ti-N bonds in the meso-macroporous TiO2-xNx was confirmed by the XPS and FT-IR spectra. The photocatalytic activity was evaluated by the photodegradation of methyl orange and rhodamine B under UV and visible-light irradiation, respectively. The significant improvement of photocatalytic activity for water contaminant decomposition under both UV and visible-light irradiation was observed, which is due to the incorporation of nitrogen into the titania lattice and the presence of the hierarchical mesomacroporous structure. (C) 2008 Elsevier B.V. All rights reserved.