Specific Surface Area and Three-Dimensional Nanostructure Measurements of Porous Titania Photocatalysts by Electron Tomography and Their Relation to Photocatalytic Activity

Abstract

Various porous titania photocatalysts are analyzed three-dimensionally in real space by electron tomography. Shapes and three-dimensional (3D) distributions of fine pores and silver (Ag) particles (2 nm in diameter) within the pores are successfully reconstructed from the 3D data. Electron tomography is applied for measuring the specific surface area of the porous structures including open and closed porosity. Calculated specific surface areas of 22.8 m(2)/g for a conventional sol-gel TiO(2) sample and 366 m(2)/g for a highly porous TiO(2) sample prepared using the Pluronic P-123 self-assembly process are compared with those measured by the general BET method. The real-space surface measurement indicates that the highly porous TiO(2) produced by the present method using block copolymers has a greater number of effective reaction sites for the degradation of methylene blue. Electron tomography shows a great potential to contribute considerably to the nanostructural analysis and design of such catalyst materials for photocatalysis.

Synthesis and Characterization of Electrospun Nanocomposite TiO2 Nanofibers with Ag Nanoparticles for Photocatalysis Applications

“…The average size of the Ag nanoparticles used to incorporate into the TiO 2 nanofibers was 15 nm. The d-spacing of the Ag (111) plane measured using fast Fourier transform (FFT) of a high-resolution TEM image was 0.23 nm, which is consistent with literature data [13]. Figure 1(a) shows a representative STEM image of the as-spun TiIP nanofibers embedded with Ag nanoparticles in 2.0% w/v with PVP as the binder.…”

2D and 3D characterization of a surfactant-synthesized TiO2–SiO2 mesoporous photocatalyst obtained at ambient temperature

“…Electron tomography, however, provides 3D projections, and this technique has proved to be a powerful tool for enabling a more complete 3D characterization of mesostructured materials. 22 In particular, electron tomography has been used successfully to characterize nanomaterials including SiO 2 23,24 and TiO 2 25,26 as well as TiO 2 -SiO 2 composites. 9 Of all the possible imaging modes available for electron tomography, those based on high angle annular dark field (HAADF) imaging in the scanning transmission electron microscope (STEM) are most suited to reveal the 3D structure of various kinds of nanomaterials because they reduce the contribution of diffraction contrast to image artifacts.…”

FE-SEM observation, and mechanism of interaction of wet agar gel in various swelling conditions using hydrophilic ionic liquid

“…Recent days electron microscopes are used as important material characterization tools due to advancement in technologies especially in high resolution performance images, high resolution analysis equipments and 3D observation abilities [1,2]. Among various electron microscopy techniques, scanning electron microscopy (SEM) has been popularly used in the scientific community over 40 years due to its wide applications in metals, semiconductors, ceramics, medical and biological field.…”