Effect of Annealing on the Structure, Morphology and Photocatalytic Activity of Surface-Fluorinated TiO2 with Dominant {001} Facets

Publication date: Available online 20 January 2020Source: Journal of Photochemistry and Photobiology A: ChemistryAuthor(s): Yugan He, Qi Yan, Xuefei Liu, Menglong Dong, Junjiao YangABSTRACTThe surface-fluorinated TiO2 crystal dominated with high energy {001} facets was synthesized by using hydrofluoric acid as capping agent which plays an exceedingly important role in controllable synthesis of 3D flower-like microstructures by self-assembling ultrathin nanosheets. The evolution of introduced fluoride species on the surface of TiO2 was studied when annealing temperature was continuously elevated in air atmosphere. X-ray diffraction results show that the as-prepared TiO2 is very stable and without phase transformation even calcination at 700 °C. Both Scanning Electron Microscope and Transmittance Electron Microscope techniques reveal that the TiO2 nanosheets are intact before calcination but are etched and form some square-like pores after calcination. Moreover, the change of fluoride species in TiO2 is discussed with the assistance of X-ray Photoelectron Spectroscopy, Thermogravimetry-Derivative Thermogravimetry, Fourier Transform Infrared Spectroscopy, and Ultraviolet-Visible spectroscopy. The results indicate that the Ti-F species is originally physical adsorbed on the TiO2 surface before calcination, then fluorine is interstitially doped in TiO2 lattice calcined at 400-500 °C, and finally fluoride species is totally removed over 600 °C. Furthermore, the photocataly...
Source: Journal of Photochemistry and Photobiology A: Chemistry - Category: Chemistry Source Type: research