Raman study of 2D anatase TiO₂ nanosheets

Herein, we present for the first time a spectroscopic study of two-dimensional (2D) anatase TiO₂ nanosheets. Previous publications demonstrated that Raman spectroscopy was mostly employed to characterize the TiO₂ nanoparticle size and the phase transition of amorphous-anatase and anatase-rutile. In this study, TiO₂ nanosheets were characterized by XRD, AFM and Raman spectroscopy, which demonstrated a shift toward higher frequency and broadening in the full width at half maximum of the characteristic E_g mode by decreasing the thickness of anatase TiO₂ with a 2D nanostructure. In contrast to the study of TiO₂ nanoparticles, the Raman vibrations can be attributed to phonon confinement in 2D TiO₂ nanosheets which can be employed to characterize the thickness of TiO₂ nanosheets. In order to effectively identify the thickness of the 2D TiO₂ nanostructure, we established a reliable method for the examination by characterizing the shifts of the E_g mode.