In-situ gas study and 3D quantitation of titania photocatalysts by advanced electron microscopy

Abstract

Titanium dioxide (TiO2) with metal nanoparticles exhibits a high photocatalytic activity by a charge separation. Recently the size of the nanoparticles has been reduced to less than 1 nm. In contrast, the size of TiO2 support particles has been kept at sub-micron sizes to ensure stability for practical use at high temperatures. For visualizing and analyzing the metal nanoparticles which are supported on different positions of those complex substrates, a high voltage transmission electron microscope(HVEM) shows a strong performance because of its high transmission capability to view whole areas of the catalysts. Electron tomography is also important to quantify the three-dimensional morphology such as size, density, surface area and nearest particle distance. Here we report the data obtained by using He-cooled 3D TEM/STEM, a newly developed 1MV high voltage environmental TEM/STEM and a 200kV aberration corrected TEM/STEM. Nanostructures of catalytic samples are characterized using these EMs as well as measurement of their chemical activity.