In situ High-Resolution Transmission Electron Microscopy of Photocatalytic Reactions by Excited Electrons in Ionic Liquid

Abstract

A transmission electron microscope (TEM) sample for observing photocatalysis in a liquid was prepared by using N,N,N-trimetyl-N-propylammonium-bis(trifluoromethanesulfonyl)imide. The ionic liquid (IL) was used as a reaction solvent. Tetrachloroauric acid was dissolved in the IL as gold ion species. Rutile particles were added in the solution as a photocatalyst. The low vapor pressure of the IL enables a diffusing system in high vacuum of TEM. Rutile particles were UV irradiated in that liquid phase. After 3 h UV irradiation, a gold particle of 8 nm diameter was grown on the TiO2 surface. Photonucleation of Au/TiO2 system was discussed from the high-resolution TEM images.

In situ direct observation of photocorrosion in ZnO crystals in ionic liquid using a laser-equipped high-voltage electron microscope

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] In general, specimen evaporation during TEM often causes critical damage to the electron gun and specimen chamber, so researchers have tried to seal such specimens in holders made from membranes of silicon nitride or SiO 2 . 1-6 By accelerating electrons through such sets of thin membranes, researchers have managed to observe specimens in solution.…”

“…In the other research, researchers have observed materials in an ionic liquid medium, which is stable and nonevaporative in ultrahigh vacuum. [7][8][9][10][11][12] However, most of those techniques must be modified for use in conventional TEM operating at 200 kV. To investigate the behavior of a specimen in liquid at high resolution, it is important to use a thinner membrane.…”

“…Conversely, conventional sample preparation methods for using ionic liquid have spread developed among chemists and biologists because it prevents charging in insulating specimens and keeps the specimen wet, [7][8][9][10][11][12] which is often advantageous. Although hardening by electron irradiation is another problem, the ease of sample preparation and stability of the ionic liquid in vacuum makes this technique very valuable.…”

Advanced and In Situ Analytical Methods for Solar Fuel Materials

“…The system was employed to observe the photodecomposition of polyhydrocarbon compounds on a TiO 2 film [123]. The same group was also able to observe photocatalytic nucleation of Au nanoparticles on a TiO 2 nanoparticle under UV irradiation [124]. Two groups have developed in situ light illumination systems for ETEM.…”

In-Situ Analysis of Optoelectronic Properties of Semiconductor Nanostructures and Defects in Transmission Electron Microscopes

“…Photocatalytic reactions in catalysts are also observable in-situ, and a photo-induced decomposition , structural transformation (Yoshida et al, 2006), and nucleation of nanostructures (Yoshida et al, 2007) are observed in a photocatalytic system. Such a structural variation is induced via a photo-induced electronic excitation, and depends on the photon energy, intensity and polarization of the illuminating light.…”