Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Tiny Step Edges, Big Step for Surface Science

09.04.2014

Experiments at the Vienna University of Technology can explain the behaviour of electrons at tiny step edges on titanium oxide surfaces. This is important for solar cell technology and novel, more effective catalysts.


Tiny step edges on titanium oxide surfaces


Jiri Pavelec, Gareth Parkinson, Benjamin Daniel, Martin Setvin (left to right)

It can be found in toothpaste, solar cells, and it is useful for chemical catalysts: titanium dioxide (TiO2) is an extremely versatile material. Alhough it is used for so many different applications, the behaviour of titanium oxide surfaces still surprises.

Professor Ulrike Diebold and her team at the Vienna University of Technology managed to find out why oxygen atoms attach so well to tiny step edges at titanium oxide surfaces. Electrons accumulate precisely at these edges, allowing the oxygen atoms to connect more strongly. In solar cells, this effect should be avoided, but for catalysts this can be highly desirable.

Microscope Pictures of Titanium Oxide Surfaces

Titanium oxide is Ulrike Diebold’s favourite material. In her latest publication, she and her team studied the behaviour of titanium oxide surfaces using scanning tunnelling microscopy and atomic force microscopy.

Titanium oxide can be used for solar cells. In the so-called Graetzel cell, an inexpensive but inefficient type of solar cell, it plays the central role. “In a solar cell, we want electrons to move freely and not attach to a particular atom”, says Martin Setvin, first author of the publication, which has now appeared in the journal “Angewandte”.

The opposite is true for catalysts: For catalytic processes, it is often important that electrons attach to surface atoms. Only at places where such an additional electron is located can oxygen molecules attach to the titanium oxide surface and then take part in chemical reactions.

Electrons Distort the Crystal Structure

Usually, it takes a considerable amount of energy to have the electrons bond to a particular atom. “When an electron is localized at a titanium atom, the electric charge of the atom is changed, and due to electrostatic forces, the titanium oxide crystal is distorted”, says Ulrike Diebold. To create this lattice distortion, energy has to be invested – and therefore this effect does not usually occur by itself.

However, the surface of titanium oxide is never completely flat. On a microscopic scale, there are tiny steps and edges, many of them with a height of only one atomic layer. At these edges, electrons can localize quite easily. The atoms at the edge only have neighbours on one side, and therefore no major lattice distortions are created when these atoms receive an additional electron and change their charge state. “We have observed that oxygen molecules can connect to the surface precisely at these locations”, says Diebold.

Better Solar Cells, More Efficient Catalysts
Important conclusions for technology can be drawn from this: for photovoltaics, such step edges should be avoided, for catalysts this newly discovered effect yields great opportunities. Surfaces could be microstructured to exhibit many such edges, making them extremely effective catalysts.

Original Publication

Further Information:

Prof. Ulrike Diebold
Institute of Applied Physics
Vienna University of Technology
Wiedner Hauptstraße 8
M: +43-664-605883467
ulrike.diebold@tuwien.ac.at

Martin Setvin, PhD
Institute of Applied Physics
Vienna University of Technology
Wiedner Hauptstraße 8
T: +43-1-58801-13470
martin.setvin@tuwien.ac.at

Florian Aigner | EurekAlert!
Further information:
http://www.tuwien.ac.at/en/news/news_detail/article/8732/

Further reports about: Atoms Cells Microscope Physics Surface TiO2 Titanium crystal structure oxygen molecule titanium titanium oxide

More articles from Life Sciences:

nachricht Faster fish thanks to nMLF neurons
25.07.2014 | Max Planck Institute of Neurobiology, Martinsried

nachricht A glimpse into the genetic basis of schizophrenia
25.07.2014 | Max Planck Institute of Psychiatry, München

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Anzeige

Anzeige

Event News

9th European Wood-Based Panel Symposium 2014 – meeting point for the wood-based material branch

24.07.2014 | Event News

“Lens on Life” - Artists and Scientists Explore Cell Divison

08.07.2014 | Event News

First International Conference on Consumer Research | ICCR 2014: Early bird deadline July 31, 2014

08.07.2014 | Event News

 
Latest News

Parched West is using up underground water, UCI, NASA find

25.07.2014 | Earth Sciences

ORNL study reveals new characteristics of complex oxide surfaces

25.07.2014 | Materials Sciences

New mass map of a distant galaxy cluster is the most precise yet

25.07.2014 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>