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Spin coated titanium-ruthenium oxide thin films
Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.ORCID iD: 0000-0001-7329-3359
Applied Electrochemistry, School of Chemical Science and Engineering, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden .
Applied Electrochemistry, School of Chemical Science and Engineering, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden .
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2013 (English)In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 536, 74-80 p.Article in journal (Other academic) Published
Abstract [en]

Substrates of different roughness spin coated with Ti0.7Ru 0.3O2 films have been evaluated as model system for fundamental studies of the industrially and scientifically interesting (Ti,Ru)O2 based electrodes. The approach allowed for much more accurate control over the material synthesis than the traditionally used brush-, dip-, or spray-coating, on titanium-metal substrates. It moreover yielded well-defined samples suitable for basic studies of the surface properties that are of fundamental importance for understanding the electrochemical functionality of the electrode. We have compared the films on silicon substrates to films prepared by spin coating the same material on titanium-metal substrates. Samples have been characterized using atomic force microscopy (AFM), X-ray diffraction, scanning electron microscopy (SEM), and cyclic voltammetry. The samples displayed a uniformity of the films appropriate for AFM characterization. The smoother the substrate the less cracks in the coating. Using easily broken silicon wafers as substrate, a straightforward sample preparation technique was demonstrated for cross-section SEM. In addition, using high spinning velocities we have deposited the oxide films directly on silicon-nitride grids, thin enough to allow for studies with transmission electron microscopy without further sample preparation.

Place, publisher, year, edition, pages
2013. Vol. 536, 74-80 p.
Keyword [en]
Atomic force microscopy; Cross-section scanning electron microscopy; Ruthenium dioxide-titanium dioxide; Spin coating; Transmission electron microscopy; X-ray diffraction
National Category
Natural Sciences
Identifiers
URN: urn:nbn:se:miun:diva-17210DOI: 10.1016/j.tsf.2013.03.044ISI: 000318974800010Scopus ID: 2-s2.0-84877696954OAI: oai:DiVA.org:miun-17210DiVA: diva2:561313
Note

Published online 2 April 2013.

Available from: 2012-10-18 Created: 2012-10-18 Last updated: 2013-08-23Bibliographically approved
In thesis
1. Nanoscaled Structures of Chlorate Producing Electrodes
Open this publication in new window or tab >>Nanoscaled Structures of Chlorate Producing Electrodes
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Sodium chlorate is mainly used for production of chlorine dioxide (a pulp bleaching agent). Sodium chlorate is produced by an electrochemical process where chloride ions (from sodium chloride dissolved in water) are oxidized to chlorine on the anodes and hydrogen is evolved on the cathodes. The anode of this process consists of a metal plate coated with a catalytically active metal oxide film. The electrocatalytic properties of the anode coating film have been widely investigated due to the great importance of these electrodes in the electrochemical industry. The material properties are, however, not as well investigated, and the studies described in this thesis are an attempt to remedy this.

Several standard material characterization methods were used, such as SEM, TEM, AFM, EDX, XRD, porosimetry and DSC. Also, a novel model system based on spin coated electrode films on smooth substrates was developed. The model system provided a way to design samples suitable for e.g. TEM, where the sample thickness is limited to maximum of 100 nm. This is possible due to the ability to control the film thickness by the spinning velocity when using the spin coating technique.

It was shown here that the anode coating has a nanostructure. It consists of grains, a few tens of nanometers across. The nanostructure leads to a large effective area and thus provides an explanation of the superior catalytic properties of these coatings. The grains were also shown to be monocrystalline. The size of these grains and its origin was investigated. The calcination temperature, the precursor salt and (if any) doping material all affected the grain size. A higher calcination temperature yielded larger grains and doping with cobalt resulted in smaller grains and therefore a larger real area of the coating. Some preparation conditions also affected the microstructure of the coating; such as substrate roughness. The microstructure is for example the cracked-mud structure. A smoother substrate gave a lower crack density.

The cathode of chlorate production is usually an uncoated metal plate, therefore 'less catalytically active'. It is, however, possible to activate the cathode by for example in situ additions to the electrolyte. It was shown here that sufficient addition of molybdate to the electrolyte resulted in a molybdenum film deposited on the cathode and thereby an increase of its surface area and an activation the hydrogen evolution reaction.

Place, publisher, year, edition, pages
Sundsvall: Mid Sweden University, 2012
Series
Mid Sweden University doctoral thesis, ISSN 1652-893X ; 134
National Category
Natural Sciences
Identifiers
urn:nbn:se:miun:diva-17206 (URN)978-91-87103-35-3 (ISBN)
Public defence
2012-11-09, M102, 13:15 (Swedish)
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Available from: 2012-10-18 Created: 2012-10-17 Last updated: 2012-11-30Bibliographically approved

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