Characterization and evaluation of fibrous SrTiO₃ prepared by hydrothermal process for the destruction of NO

Fibrous SrTiO₃ particles were prepared by a hydrothermal reaction method using strontium hydroxide octahydrate and protonic layered tetratitanate as raw materials. The samples were characterized by X-ray diffraction, X-ray photoelectron spectrometer, scanning electron microscopy, nitrogen adsorption-desorption isotherm measurements and diffusion reflectance spectra. SrTiO₃ existed as two different morphologies of particles, i.e., fibrous particles and nanosized particles which attached to the surface of former ones. SrTiO₃ seemed to be formed by two different ways. One way is a direct reaction between H₂Ti₄O₉ and Sr(OH)₂ and the other is a two-step reaction involving transformation of H₂Ti₄O₉ to monoclinic TiO₂ followed by a reaction with Sr(OH)₂. Fibrous nitrogen doped SrTiO₃, which exhibited excellent visible light responsive photocatalytic activity, was prepared by the heat treatment of fibrous SrTiO₃ under the flow of ammonia gas at 600 °C for 3 h. Under the irradiation of light with wavelengths larger than 400 and 290 nm, the photocatalytic activities of fibrous SrTiO₃ were 2.4 and 1.3 times greater than those of spherical SrTiO₃ prepared by the solid-state reaction.