Fiber-like TiO₂ Nanomaterials with Different Crystallinity Phases Fabricated via a Green Pathway

Fiber-like TiO(2) nanomaterials were designed and created, for the first time, by in situ synthesis of TiO(2) nanoparticles in regenerated cellulose fibers in the wet state, followed by calcination at 400-800 °C to remove the cellulose matrix. The cellulose fibers were prepared in an NaOH/urea aqueous system with cooling via an industrial machine. The structure and properties of the fiber-like TiO(2) nanomaterials were characterized with scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and photocatalytic degradation tests. The results revealed that the mean diameter of the fiber-like TiO(2) nanomaterials, which consisted of TiO(2) nanoparticles with a mean size from 21 to 37 nm, was 7-8 μm. The TiO(2) nanomaterials exhibited different crystallinity phases from anatase to rutile, depending on the calcinating temperature. With a decrease in the calcinating temperature from 800 to 400 °C, the surface area of the TiO(2) nanomaterials increased. The photocatalytic activity for the degradation of methyl orange of the anatase T-400 fibers calcined at 400 °C was the highest, compared with that at 600 and 800 °C. This work provided a simple and "green" pathway for the preparation of inorganic nanomaterials with different crystal structures by using porous regenerated cellulose matrix.