Novel Sol-Gel Synthesis of TiO2 Spherical Porous Nanoparticles Assemblies with Photocatalytic Activity

Abstract

For this study, the synthesis of TiO2 nanomaterials was performed via a novel sol-gel method employing titanium butoxide as a metal precursor, Pluronic F127 as a templating agent, toluene as a swelling agent, and acidic water or ethanol as the reaction solvents. The method was designed by tailoring certain reaction parameters, such as the sequence of toluene addition, magnetic stirring, the type of reaction solvent, and the calcination conditions. Analysis of the specific surface area and porosity was carried out via N2 physisorption, whereas the morphological features of the solids were investigated via transmission electron microscopy. The crystalline structure of both the dried powders and the calcined materials was evaluated using X-ray diffraction analysis. It transpired that the different phase compositions of the solids are related to the specific synthesis medium employed. Under the adopted reaction conditions, ethanol, which was used as a reaction solvent, promoted the local arrangement of dispersed anatase particles, the specific arrangement of which does not lead to rutile transformation. Conversely, the use of water alone supported high-particle packing, evolving into a rutile phase. The photodegradation of Rhodamine B was used as a target reaction for testing the photocatalytic activity of the selected samples.

Oxygen Level Controlled Polymorphic Transformation in Sol–Gel Processed Electrospun TiO2 Nanofibers

“…The surface free energy of rutile is higher than that of the anatase phase when the particle size is smaller than the critical size, 14 nm; therefore, anatase becomes more stable below this critical size . Researchers have stabilized this phase involving various synthesis techniques like sol–gel, solvothermal, hydrothermal, and atmospheric pressure plasma deposition through controlling precursors, oxygen vacancies, and doping. − However, polycrystalline nanoparticles of anatase TiO 2 possess numerous crystal domains featuring varied orientations and crystal facets, potentially resulting in a reduced surface area . Hence, it has been a challenge to obtain anatase TiO 2 nanoparticles with increased surface areas.…”