Effect of pH on the Formation of Amorphous TiO2 Complexes and TiO2 Anatase during the Pyrolysis of an Aqueous TiCl4 Solution

Abstract

The titanium dioxide (TiO2) nanostructures resulted by the pyrolysis of titanium tetrachloride (TiCl4) at a low temperature of 80 °C were found to be a mixture of amorphous TiO2 complexes and anatase nanostructures, whose ratio depends on the pH of the pyrolysis medium. At a low pH level, the resulting TiO2 nanostructures are predominantly anatase and gradually shift to amorphous TiO2 complexes as the pH level increases. Moreover, the amorphous TiO2 complexes can convert back to anatase nanostructures by a post-heating treatment, and can then transform to rutile with elevating temperature. Amongst the TiO2 nanostructures recovered from the amorphous TiO2 complexes, anatase appears to be the most effective photocatalyst in the decomposition of methylene blue.

A Metatitanic Acid Particulate Xerogel: Green Synthesis, Structure Determination, and Detailed Characterization

“…The sample TS_2 shows the successful formation of pure-phase tetragonal anatase (JCPDS 89-4921). All other samples also have the same phase with broad peaks due to the nanostructure nature of these samples . Also, the high-resolution TEM images confirm the interference fringes, suggesting the presence of small crystallites.…”

“…All other samples also have the same phase with broad peaks due to the nanostructure nature of these samples. 37 Also, the high-resolution TEM images confirm the interference fringes, suggesting the presence of small crystallites. Diffraction patterns of all of the studied samples are present in Figure S1 .…”

Niobium and Fluorine Dually Doped Titanium Oxide Nanosheet Arrays for Selective Dual-Band Electrochromic Applications

“…With increasing Nb doping concentration, a significant peak shift and peak broadening of the lattice toward lower diffraction angles were also observed, which can be attributed to lattice expansion and reduction of the crystal size, respectively. , The lattice expansion suggests successful doping of Nb into the TiO 2 crystal structure owing to the substitution of Ti 4+ (radius: 0.605 Å) with a larger Nb 5+ (radius: 0.64 Å). , The microstructure of Nb-doped TiO 2 NSs was further characterized by Raman spectroscopy (Figure b). The typical anatase peaks at 140 cm –1 ( E g ), 395 cm –1 ( B 1g ), 517 cm –1 ( A 1g ), and 639 cm –1 ( E g ) were observed in all samples . With the increase of the Nb doping level, the strong anatase Raman peak at 140 cm –1 associated with O–Ti–O bending broadened and shifted to a higher energy (145 cm –1 ), due to Nb–O–Ti bond formation. , The B 1g mode associated with the stretching of the Ti–O bond was found to shift slightly toward a lower wavenumber, and the observed shift also confirmed the doping of Nb into the TiO 2 lattice.…”

“…The typical anatase peaks at 140 cm −1 (E g ), 395 cm −1 (B 1g ), 517 cm −1 (A 1g ), and 639 cm −1 (E g ) were observed in all samples. 35 With the increase of the Nb doping level, the strong anatase Raman peak at 140 cm −1 associated with O−Ti−O bending broadened and shifted to a higher energy (145 cm −1 ), due to Nb−O−Ti bond formation. 36,37 The B 1g mode associated with the stretching of the Ti−O bond was found to shift slightly toward a lower wavenumber, and the observed shift also confirmed the doping of Nb into the TiO 2 lattice.…”