Porous Anatase Nanoparticles with High Specific Surface Area Prepared by Miniemulsion Technique

Abstract

A simple template-free approach to generate spherical porous anatase nanoparticles by combining the sol-gel process with the inverse miniemulsion technique is reported. These as-synthesized particles of about 200 nm in diameter consist of aggregated small anatase crystallites of several nanometers, thus leading to a high specific surface area of more than 300 m 2 • g -1 , even after calcination at 400 °C. The only employed surfactant is a block copolymer (P(E/B-b-EO)), which stabilizes the aqueous droplets with the water-soluble precursor bis(2-hydroxyethyl)titanate (EGMT) in the organic phase but also leads to aggregation and pore formation inside the particles. The lower relative rates of hydrolysis and condensation compared to the commonly used titanium alkoxides allow convenient handling in miniemulsion. Here we report the effects of synthesis conditions, such as the amount of surfactant, the composition of the dispersed phase, and the reaction and calcination temperature, on the particle size, porosity, crystallite size, crystallite phase, and specific surface area of the obtained nanoparticulate material. After removing the continuous phase, the obtained powders were characterized before and after calcination by transmission (TEM) and scanning electron microscopy (SEM), X-ray diffraction (XRD), and nitrogen sorption (BET).

ZnO Nanostructures for Dye‐Sensitized Solar Cells

“…[226] Rossmanith et al reported on the fabrication of porous-structured TiO 2 by using glycol-modified titanate (bis(2-hydroxyethyl)titanate, EGMT) as the precursor material and an amphiphilic block copolymer (P(E/ B-b-EO)) as the surfactant. [227] The size of the synthesized TiO 2 spheres is typically about 200 nm in diameter. Impressively, these spheres are formed by interconnected nanocrystallites with the size of several nanometers, leading to a high specific surface area of more than 300 m 2 g…”

Synthesis of mesoporous TiO2−xNx spheres by template free homogeneous co-precipitation method and their photo-catalytic activity under visible light illumination

“…It has also been investigated that crystallite sizes greatly affect the catalytic activity. Smaller the crystallite size, higher is the photocatalytic activity in anatase TiO 2 [60,61]. Thus anatase TiO 2 having below 10 nm size shows extraordinary catalytic properties.…”

Recent Progress in the Synthesis of Spherical Titania Nanostructures and Their Applications

“…[ 76 ] Porous nanospheres consisting of ≈ 5 nm titania nanocrystals and having a high surface area of 321 m 2 g − 1 were fabricated in the presence of 5 wt% block copolymer surfactant.…”