Jump to main content
Jump to site search
SCHEDULED MAINTENANCE Close the message box

Maintenance work is planned for Monday 16 August 2021 from 07:00 to 23:59 (BST).

Website performance may be temporarily affected and you may not be able to access some PDFs or images. If this does happen, refreshing your web browser should resolve the issue. We apologise for any inconvenience this might cause and thank you for your patience.


Issue 18, 2001

On the preparation and composition of potassium promoted iron oxide model catalyst films

Author affiliations

Abstract

Potassium promoted iron oxide model catalyst films were prepared by deposition of potassium onto epitaxial Fe3O4(111) films at 200 K, followed by annealing in the range 200 to 970 K. Their formation and composition were investigated by X-ray photoelectron spectroscopy (XPS) in combination with thermal desorption spectroscopy (TDS) and thermodynamic considerations. Already at 300 K a solid-state reaction occurred and the iron oxide was partly reduced. Around 700 K a KFeO2 phase was identified which transformed at higher temperatures into KxFe22O34(0.67<x<4). This transformation started from the bulk of the film so that initially a potassium-rich KFeO2 layer was formed on top of KxFe22O34. The formation of a single-crystalline KxFe22O34 (x = 0.67) layer, which is terminated by a submonolayer of potassium, is assumed to occur at 970 K. For a certain potassium content, this surface develops a well ordered phase with a (2 × 2) superstructure. The potassium containing phases are not stable in water atmosphere: In 10−8 mbar H2O, potassium hydroxide forms, then decomposes and desorbs beyond 400–500 K resulting in a potassium-depleted near-surface layer.

Article information


Submitted
15 May 2001
Accepted
17 Jul 2001
First published
30 Aug 2001

Phys. Chem. Chem. Phys., 2001,3, 4141-4153
Article type
Paper

On the preparation and composition of potassium promoted iron oxide model catalyst films

Y. Joseph, G. Ketteler, C. Kuhrs, W. Ranke, W. Weiss and R. Schlögl, Phys. Chem. Chem. Phys., 2001, 3, 4141 DOI: 10.1039/B104263G

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.


Social activity

Search articles by author

Spotlight

Advertisements