Photoluminescence: A very sensitive tool to detect the presence of anatase in rutile phase electrospun TiO₂ nanofibers

This paper reports on the synthesis and the characterization of titanium dioxide (TiO₂) nanofibers prepared by electrospinning. The samples were annealed at various temperatures in air for 4 h. The as-spun and annealed TiO₂/PVP composite nanofibers were characterized by scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy analysis (EDX), X-ray diffraction (XRD), Raman spectroscopy and photoluminescence (PL). The results show that the heat treatment has an effect on the crystallization process. Even if the XRD data shows a complete anatase-to-rutile transition in the TiO₂ nanofibers at 900 °C, photoluminescence reveals a small portion of anatase in rutile sample. This observation proved that photoluminescence is a very sensitive tool to detect the presence of anatase in rutile phase TiO₂ nanostructures.