TEM analysis of Pt-particles embedded on TiO2 exhibiting high photocatalytic activity

Abstract

Fine particles of semiconductive rutile TiO2 supporting ultra-fine-particles of Pt were studied by high-resolution analytical electron microscopy. The embedded Pt particles were prepared by decomposing a colloidal organic-Pt complex. This particle system is known to exhibit remarkably high photocatalytic activities. In this study, the structural aspects of the high photoactivity were examined by high-resolution imaging, X-ray mapping by energy dispersive spectroscopy and electron energy-loss spectroscopy. As a result, the ultra-fine particles are composed only of Pt and their size distribution is narrow with a mean diameter of 3 nm. The Pt particles with nm-sizes were found to grow epitaxially on rutile TiO2 having the following crystallographic relationship; [110] (001 )Pt // [001] (110)TiO2. This result supports the expected mechanism that the photo-excited electrons efficiently transfer from TiO2 to Pt and promote the reduction of O2 to O2− ions which will be able to react with organic molecules at the surface.