Synthesis of nitrogen-doped titanium oxide nanostructures via a surfactant-free hydrothermal route

Nitrogen-doped titanium oxides nanostructures were synthesized by a new method proposed here from titanium oxysulfate precursor in a NH4OH solution under hydrothermal conditions without any extra templates as structure driving agents. The material synthesized with NH4OH was an ammonium titanate and showed curled nanosheets. nanofibers or nanorods morphologies depending on the molar ratio of NH4OH to titanium precursor and the hydrothermal temperature. The nanofibrous titanates had a high surface area over 500 m(2) g(-1) and a pore volume of 0.72 cm(3) g(-1). The calcination of as-synthesized material at 673 K produced a titanium oxynitride TiO2-xNx with anatase phase, which absorbed visible light. Ion exchange of ammonium ion of the titanate with sodium Na2Ti3O7-xNx enhanced the thermal stability of the titanate phase.