In-situ Observation of Nano-Particulate Gold Catalysts by Closed-Type Environmental Transmission Electron Microscope

Tadahiro Kawasaki, Hiroki Murase, Norihiro Imaeda, Cui Zipeng, Takuya Miura, Takaomi Matsutani and Takayoshi Tanji

Abstract: We have developed a closed-type environmental-cell (E-cell) transmission electron microscope (TEM) enabling to observe catalyst specimens reacted at ambient conditions. As a part of the developed system, a coaxial-type gas-flow specimen holder has been invented. A hybrid membrane has been also developed as a window material of the E-cell, which consists of an amorphous carbon film and a silicon nitride thin layer. The membrane showed high performances such as less deterioration of spatial resolution, high toughness for pressure difference, and high stability for electron beam irradiation. As an application of our developed system, nanoparticulate gold catalysts supported on TiO₂ anatase substrates were observed dynamically at a condition of a selective oxidation of propylene. In-situ observations by the E-cell TEM revealed that product materials of catalytic reaction were formed from the perimeters of the gold/TiO₂ interfaces.

Key words: environmental transmission electron microscopy (ETEM), membrane, catalyst, gold nano-particle, propylene