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.

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.


Tiny step edges on titanium oxide surfaces


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

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 Killer sea snail a target for new drugs
07.07.2015 | University of Queensland

nachricht First images of dolphin brain circuitry hint at how they sense sound
07.07.2015 | Emory Health Sciences

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Surfing a wake of light

Researchers observe and control light wakes for the first time

When a duck paddles across a pond or a supersonic plane flies through the sky, it leaves a wake in its path. Wakes occur whenever something is traveling...

Im Focus: Light-induced Magnetic Waves in Materials Engineered at the Atomic Scale

Researchers explore ultrafast control of magnetism across interfaces: A new study discovers how the sudden excitation of lattice vibrations in a crystal can trigger a change of the magnetic properties of an atomically-thin layer that lies on its surface.

A research team, led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter at CFEL in Hamburg, the University of Oxford, and the...

Im Focus: Viaducts with wind turbines, the new renewable energy source

Wind turbines could be installed under some of the biggest bridges on the road network to produce electricity. So it is confirmed by calculations carried out by a European researchers team, that have taken a viaduct in the Canary Islands as a reference. This concept could be applied in heavily built-up territories or natural areas with new constructions limitations.

The Juncal Viaduct, in Gran Canaria, has served as a reference for Spanish and British researchers to verify that the wind blowing between the pillars on this...

Im Focus: X-rays and electrons join forces to map catalytic reactions in real-time

New technique combines electron microscopy and synchrotron X-rays to track chemical reactions under real operating conditions

A new technique pioneered at the U.S. Department of Energy's Brookhaven National Laboratory reveals atomic-scale changes during catalytic reactions in real...

Im Focus: Iron: A biological element?

Think of an object made of iron: An I-beam, a car frame, a nail. Now imagine that half of the iron in that object owes its existence to bacteria living two and a half billion years ago.

Think of an object made of iron: An I-beam, a car frame, a nail. Now imagine that half of the iron in that object owes its existence to bacteria living two and...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

World Conference on Regenerative Medicine in Leipzig: Last chance to submit abstracts until 2 July

25.06.2015 | Event News

World Conference on Regenerative Medicine: Abstract Submission has been extended to 24 June

16.06.2015 | Event News

MUSE hosting Europe’s largest science communication conference

11.06.2015 | Event News

 
Latest News

Down to the quantum dot

07.07.2015 | Physics and Astronomy

Tundra study uncovers impact of climate warming in the Arctic

07.07.2015 | Earth Sciences

Transition from 3 to 2 dimensions increases conduction, MIPT scientists discover

07.07.2015 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>