Tuning the porosity and surface characteristics of nanoporous titania using non-ionic surfactant reverse micelles

Abstract

Nanoporous titania was prepared from non-ionic surfactant reverse micelles (e.g. Triton-X) and the effects of the chain length of the surfactants and calcination temperature of the precursor gels on the surface properties of the product (mesoporous titania) were investigated. The studies included sample characterization of the precursor gels from the titania samples characterized by UV-Vis, ATR-FTIR, XRD, TGA/DSC and the titania samples by N 2 -adsorption BET, XRD, FT-IR, UV-Vis diffuse reflectance and SEM measurements after calcination at 400 C, 500 C, 600 C, 700 C and 800 C. According to the experimental results, generally increasing the length of the polar tail of Triton-X results in an increased specific surface area and volume, and an average pore diameter of the solids. Moreover, increasing the length of the polar tail is associated with a smaller crystallite size and higher thermal stability of the materials. Finally, a nucleation mechanism of the titania particles within the aqueous centre of the reversed micelles is proposed.

Surface properties of ceria synthesised using Triton-X based reverse microemulsions

“…Moreover, this behavior coincides with the corresponding behavior of TiO 2 solids indicating on similar interaction mechanisms. 12 The XRD and BET surface data are corroborated by the DRUV-Vis data (Fig. 7) corresponding to ceria solids obtained aer direct and indirect calcination at 400 C for 2 h of the three different Triton-X gels.…”

“…The measurements of UV-Vis absorption spectrophotometry, isothermal N 2 adsorption/desorption (employing a slit-shaped pore model), powder X-ray diffraction spectroscopy, Fourier-Transform Infrared spectrophotometry, ATR-FTIR (attenuated total reectance) Fourier-transform infrared spectroscopy, UV-Vis diffuse reectance solid state spectroscopy, thermogravimetric analysis, thermal differential scanning calorimetry and scanning electron microscopy were carried out as described elsewhere. 12…”

Comparison of Surface Characteristics of Mesoporous Titania Prepared in Matrix-Free Solutions and Using Triton X Reverse Micelles

“…It is noteworthy, that solids from solvothermal method above 500˚C present the greatest energy gap due to their increased thermal stability.According to SEM measurements titania solids obtained from solvothermal methods are very well-formed and fine-grained powders with a mean size of aggregates around 48 μm(Figure 9(a)andFigure 10(a)). The mean size value of TiO 2 aggregates obtained using reverse micelles is 130 μm[17]. According to SEM images(Figure 9andFigure 10) increasing calcination temperature affects the mean size of particles obtained from aqueous colloidal systems and the values are 48, 61 and 87 μm for 400˚C, 600˚C and 700˚C, respectively.…”

“…The titania gels have been prepared by mixing the Ti(O i Pr) 4 precursor compound with the three different reversed micelle mixtures of Triton X-100 (extra pure, Fisher Chemical), Triton X-114 (extra pure, Sigma-Aldrich) and Triton X-45 (extra pure, Sigma-Aldrich) as described elsewhere [17].…”

“…Regarding the matrix-free methods in aqueous and organic solutions, there are many bibliographic data that describe synthetic pathways of TiO 2 solids resulting in high surface area related to the porosity and particle size of the solids [17] [21]. The matrix-free methods are the solvothermal and hydrothermal processes, pyrolysis, thermal decomposition, aqueous alkalic/acidic precipitation, liquid, and solid combustion techniques, mechanochemical and electrochemical methods, sol-gel procedure, gas phase condensation, microwaves heating synthesis and ultrasound methods.…”