J. Lahtinen

An XPS study of metallic three-way catalysts : the effect of additives on platinum, rhodium, and cerium

Abstract The effect of Zr, Si, La, and Ba on the thermal aging of Pt, Rh, and Ce in automotive exhaust gas catalysts supported on metal foils was studied with X-ray photoelectron spectroscopy (XPS). Platinum was in metallic state under all circumstances studied in this work. Rhodium was partially (about 30%) oxidized already at room temperature. The decreases in the binding energies of the reduced noble metals due to aging was explained in terms of particle growth. The binding energy of rhodium oxide increased during aging indicating rhodium diffusion into alumina. Cerium was oxidized during aging. It was found that in the lanthanum containing catalysts the binding energies of platinum and rhodium were below the values for bulk metals, and the degree of oxidation of cerium was lower than in the other samples. It was concluded that the presence of lanthanum facilitated the reduction of the noble metals and cerium.

Influence of hydrodynamics on many-particle diffusion in 2D colloidal suspensions

Abstract.We study many-particle diffusion in 2D colloidal suspensions with full hydrodynamic interactions through a novel mesoscopic simulation technique. We focus on the behaviour of the effective scaled tracer and collective-diffusion coefficients

Adsorption and desorption measurements of CO and O2 on cobalt

D_{\rm T}(\rho) / D_0

Studies of Mg—O overlayers on Co(0001): growth mode and CO chemisorption properties

and

Vacancy-type defect distributions near argon sputtered Al(100) surface studied by variable-energy positrons and molecular dynamics simulations

D_{\rm C}(\rho) / D_0

An XPD and ISS study of the (2 × 2)-(CO + K) coadsorption structure on Co(0001)

, respectively, where D0 is the single-particle diffusion coefficient, as a function of the density of the colloids

Chromium deposition on ordered alumina films: An x-ray photoelectron spectroscopy study of the interaction with oxygen

\rho

Adsorption of CO on Mg-promoted Co(poly)

. At low Schmidt numbers

Growth and oxidation of Mg films on polycrystalline cobalt

Sc \sim 1

Promotion of CO dissociation by magnesia on Co(0001)

, we find that hydrodynamics has essentially no effect on the behaviour of