GROWTH, MORPHOLOGY, INTERFACIAL EFFECTS AND CATALYTIC PROPERTIES OF Au ON TiO₂

Abstract

We survey recent studies and present new data on the growth, interactions, structure and chemistry of gold deposited on TiO 2(110) surfaces. The noble metal Au on TiO 2(110) is a model system for weak interaction of a metal with an oxide substrate; it is also of interest because Au on TiO 2 has unusually high activity as a catalyst for CO oxidation at room temperature. In this review, we present results on the growth of ultrathin films of Au on TiO 2(110), as well as the morphology, interface formation, epitaxy, structure and electronic properties of Au on TiO 2 single crystal and planar films. The results are compared to studies of Au on high-surface-area TiO 2 catalysts in an attempt to bridge the gap between surface science experiments and the high pressure conditions of catalyst operation.

Bonding of Gold Nanoclusters to Oxygen Vacancies on RutileTiO2(110)

“…It is not surprising that larger clusters formed after growth at, or annealing to, RT are found at step edges since the step edges can be considered as a collection of oxygen vacancies. The bimodal growth model differs from other models proposed to explain Au growth on TiO 2 110 [17,18]. Parker et al [18] have shown that the onset of 3D growth corresponds to a coverage of 0.086 ML on the stoichiometric TiO 2 110 surface and 0.15 ML on the thermally reduced surface.…”

Structure and Formation Model of Ag/TiO2 and Au/TiO2 Nanoparticles Synthesized through Ultrasonic Spray Pyrolysis

“…Lai et al [15] studied the most stable surface (1 1 0) of rutile which includes five-fold coordinated Ti atoms rows and two-fold coordinated bridging O atoms. It was found out that nucleation of metal nanoclusters initiated at surface defects, which is thermodynamically favorable due to the high adsorption energy and Ti cation sites between bridging oxygen rows [16]. On the other hand, the most stable surface of anatase is reported by Vittadini et al [17], as (1 0 1) which serves five-fold coordinated O anions and five-fold coordinated Ti atoms as mostly preferential nucleation sites of noble metal clusters.…”

“…The equilibrium shape of a cluster is determined by the balance of the forces between the surface and the interfacial energy. Isotropy of clusters varies the mechanism as given in Figure 1 [16].…”

“…In order to have control over the final microstructure it is important to understand the formation mechanism of these complex nanoparticles, which is led by nucleation and growth. Different nucleation behavior was reported of noble metals on different TiO2 polymorphs [15][16][17]. Lai et al [15] studied the most stable surface (1 1 0) of rutile which includes five-fold coordinated Ti atoms rows and two-fold coordinated bridging O atoms.…”

Potassium-Promoted Iron Oxide Model Catalyst Films for the Dehydrogenation of Ethylbenzene: An Example for Complex Model Systems

“…Recently, even more complex catalyst model systems have been prepared. These include metal particles deposited on oxide supports [7][8][9], as well as alkali metal promoted model catalyst films [10][11][12]. The interaction of potassium with well-defined oxide surfaces has been subject to several investigations [10][11][12][13][14][15][16][17][18].…”