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

Abstract

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 °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 μm–1.2 μm) 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.