Sol-Gel Synthesis of TiO₂ Nanocrystalline Particles with Enhanced Surface Area through the Reverse Micelle Approach

Abstract

Titania nanocrystalline particles were synthesized by hydrolysis-condensation of titanium tetraisopropoxide in water-in-oil micellar solutions of water/cyclohexane/Triton X-100 system, and the effects of reflux time and water-to-surfactant molar ratio on the particle uniformity, crystallinity, and surface area were studied. Several characterization techniques including TEM and SEM, as well as X-ray diffraction and FT-IR spectroscopy, helium pycnometry, and nitrogen physisorption, were employed to evaluate the particle density and dimensions, crystallite size, surface area value, and the porosity features in the as-prepared condition and also after thermal treatment at 500°C. The results show that all treated samples are dense nanocrystalline anatase particles with BET surface area values over 100 m2·g−1 and primary particle size of 10–15 nm. However, for the as-prepared samples, as the reflux time increases, a better purification of particles from the synthesis environment is resulted, leading to denser and more crystalline powders with smaller particle size and higher BET surface area values culminating in 179 m2·g−1 for 24 hours of refluxing. Moreover, decreasing the water-to-surfactant molar ratio from 10 to 5 and 2 increases the particles surface area to 239 and 224 m2·g−1, respectively, at the expense of slight density and crystallinity degradation and considerable prolongation of surfactant removal step. Supportively, the comparison between photocatalytic activities of as-prepared samples also evidences the effectiveness of reflux time extension on improving the sample features and enhancing their functionality. This study can highlight how the earlier synthesis steps can influence the evolution of the structure of the final products.

The Influence of the Precursor’s Nature and Drying Conditions on the Structure, Morphology, and Thermal Properties of TiO2 Aerogels

“…The SEM investigation results show a typical morphology for micrometer-designed aerogel-like powders ( Figure 9 ). Micrometer-sized particles are visible in the samples [ 12 , 31 , 42 ]. The particles are highly polydispersed and the smallest ones of these are agglomerated.…”

Titanium Dioxide in Chromogenic Devices: Synthesis, Toxicological Issues, and Fabrication Methods

“…Titanium tetraisopropoxide (TTIP) in water-in-oil micellar solutions of water/cyclohexane/Triton X-100 was adopted to synthesize anatase TiO 2 NPs by a hydrolysis-condensation process. In this way, the authors obtained small NPs with a particle size of 10-15 nm, due to the gradual hydrolysis of titanium alkoxide [47].…”

Photocatalytic Porous Silica-Based Granular Media for Organic Pollutant Degradation in Industrial Waste-Streams

“…In turn, increasing surface area enhances the efficiency and effectiveness of catalysis because of the homogenous structure created [33,34]. Recent advancements in sol-gel synthesis processes indicate that controlling the molar ratio of water-to-surfactant may increase the BET surface area by up to 58% [35]. Sol-gel synthesis is cost-effective, requires low energy consumption, and has the potential to produce zero waste during production [36].…”