Nitrogen-doped TiO2 fibers for visible-light-induced photocatalytic activities

Nitrogen-doped TiO2 fibers (N-TiO2 Fs) were successfully and efficiently fabricated using titanium diisopropoxide bis(acetylacetonate) and polyvinylpyrrolidone (PVP) as a carrier polymer and nitrogen source via centrifugal spinning and subsequent calcination methods. XRD analysis confirmed that N-TiO2 Fs contains only anatase and rutile phases. XPS analysis revealed that N-atoms (from PVP) were successfully incorporated into the lattice of TiO2 whereas DTA and FTIR analysis confirmed that calcination at 550 degrees C for 1 h is appropriate to remove all organic impurities from the N-TiO2 Fs. SEM images showed that the N-TiO2 Fs of diameter (0.65 mu m-1.2 mu m) were produced and controlled with the amount of Ti-precursor. BET analysis confirmed that the addition of commercial TiO2 nanoparticles increased the specific surface area of the N-TiO2 Fs. UV-Vis diffuse reflectance measurements showed that N-TiO2 Fs exhibited a stronger light absorption in the visible region and a red-shift which is responsible for narrow band gap energy owing to the presence of N-atoms in the TiO2 lattice. This results in enhanced photocatalytic activity of the synthesized N-TiO2 Fs for degradation of methylene blue under visible light irradiation.