Analytical TEM observation of Au and Ir deposited on rutile TiO2.

As a model catalyst, gold and iridium were co-deposited on a single crystal of rutile TiO2 using the deposition precipitation method in order to clarify the synergetic effect of the combination of Au with Ir on the catalytic performance of the oxidative decomposition of odour and dioxins. Analyses by means of high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy and electron energy-loss spectroscopy revealed that pillars of IrO2 grew on the TiO2 substrate to each of which one Au nanoparticle was attached. This mushroom-like structure appeared to be formed by self-organization of Au, Ir and oxygen. Epitaxial contact was observed between the Au nanoparticle/IrO2 pillar and IrO2 pillar/TiO2 substrate interfaces. The growth process of the structure was investigated by transmission electron microscope observations of the Au-Ir complex before and after heating in air.