Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Stickier than expected: Hydrogen binds to graphene in 10 femtoseconds

06.05.2019

Bound for only ten quadrillionths of a second

Graphene is celebrated as an extraordinary material. It consists of pure carbon, only a single atomic layer thick. Nevertheless, it is extremely stable, strong, and even conductive. For electronics, however, graphene still has crucial disadvantages.


The hydrogen atom (blue) hits the graphene surface (black) and forms an ultra-fast bond with a carbon atom (red). The high energy of the impinging hydrogen atom is first absorbed by neighboring carbon atoms (orange and yellow) and then passed on to the graphene surface in form of a sound wave

Credit: Oliver Bünermann / Max Planck Institute for Biophysical Chemistry & University of Göttingen

It cannot be used as a semiconductor, since it has no bandgap. By sticking hydrogen atoms to graphene such a bandgap can be formed. Now researchers from Göttingen and Pasadena (USA) have produced an "atomic scale movie" showing how hydrogen atoms chemically bind to graphene in one of the fastest reactions ever studied. (Science, April 25, 2019)

The international research team bombarded graphene with hydrogen atoms. "The hydrogen atom behaved quite differently than we expected," says Alec Wodtke, head of the Department of Dynamics at Surfaces at the Max Planck Institute (MPI) for Biophysical Chemistry and professor at the Institute of Physical Chemistry at the University of Göttingen.

"Instead of immediately flying away, the hydrogen atoms 'stick' briefly to the carbon atoms and then bounce off the surface. They form a transient chemical bond," Wodtke reports.

And something else surprised the scientists: The hydrogen atoms have a lot of energy before they hit the graphene, but not much left when they fly away. Hydrogen atoms lose most of their energy on collision, but where does it go?

To explain these surprising experimental observations, the Göttingen MPI researcher Alexander Kandratsenka, in cooperation with colleagues at the California Institute of Technology, developed theoretical methods, which they simulated on the computer and then compared to their experiments.

With these theoretical simulations, which agree well with the experimental observations, the researchers were able to reproduce the ultra-fast movements of atoms forming the transient chemical bond. "This bond lasts for only about ten femtoseconds - ten quadrillionths of a second. This makes it one of the fastest chemical reactions ever observed directly," Kandratsenka explains.

"During these ten femtoseconds, the hydrogen atom can transfer almost all its energy to the carbon atoms of the graphene and it triggers a sound wave that propagates outward from the point of the hydrogen atom impact over the graphene surface, much like a stone that falls into water and triggers a wave," says Kandratsenka.

The sound wave contributes to the fact that the hydrogen atom can bind more easily to the carbon atom than the scientists had expected and previous models had predicted.

The results of the research team provide fundamentally new insights into chemical bonding. In addition, they are of great interest to industry. Sticking Hydrogen atoms to graphene can produce a bandgap, making it a useful semiconductor and much more versatile in electronics.

The effort involved in setting up and running these experiments was enormous, revealed Oliver Bünermann, project group leader at the University of Göttingen. "We had to carry them out in ultra-high vacuum to keep the graphene surface perfectly clean."

The scientists also had to use a large number of laser systems to prepare the hydrogen atoms before the experiment and to detect them after the collision. According to Bünermann, the excellent technical staff in the workshops at the MPI for Biophysical Chemistry and at the University of Göttingen were essential to the project's success.

###

Further information: http://www.mpibpc.mpg.de/wodtke and http://www.uni-goettingen.de/en/212047.html

Original publication: Hongyan Jiang, Marvin Kammler, Feizhi Ding, Yvonne Dorenkamp, Frederick R. Manby, Alec. M. Wodtke, Thomas F. Miller, Alexander Kandratsenka, Oliver Bünermann: Imaging covalent bond formation by H atom scattering from graphene. Science 364, 6438, 379-382, doi: 10.1126/science.aaw6378 (2019).

Contact:

Professor Alec Wodtke,
Group of Dynamics at Surfaces
MPI for Biophysical Chemistry & University of Göttingen
Phone: +49 551 201-1261
Email: alec.wodtke@mpibpc.mpg.de

Media Contact

Melissa Sollich
melissa.sollich@uni-goettingen.de
49-055-139-26228

http://www.uni-goettingen.de 

Melissa Sollich | EurekAlert!
Further information:
https://www.uni-goettingen.de/en/3240.html?id=5431
http://dx.doi.org/10.1126/science.aaw6378

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Artificial neural network resolves puzzles from condensed matter physics: Which is the perfect quantum theory?

For some phenomena in quantum many-body physics several competing theories exist. But which of them describes a quantum phenomenon best? A team of researchers from the Technical University of Munich (TUM) and Harvard University in the United States has now successfully deployed artificial neural networks for image analysis of quantum systems.

Is that a dog or a cat? Such a classification is a prime example of machine learning: artificial neural networks can be trained to analyze images by looking...

Im Focus: Extremely hard yet metallically conductive: Bayreuth researchers develop novel material with high-tech prospects

An international research group led by scientists from the University of Bayreuth has produced a previously unknown material: Rhenium nitride pernitride. Thanks to combining properties that were previously considered incompatible, it looks set to become highly attractive for technological applications. Indeed, it is a super-hard metallic conductor that can withstand extremely high pressures like a diamond. A process now developed in Bayreuth opens up the possibility of producing rhenium nitride pernitride and other technologically interesting materials in sufficiently large quantity for their properties characterisation. The new findings are presented in "Nature Communications".

The possibility of finding a compound that was metallically conductive, super-hard, and ultra-incompressible was long considered unlikely in science. It was...

Im Focus: Modelling leads to the optimum size for platinum fuel cell catalysts: Activity of fuel cell catalysts doubled

An interdisciplinary research team at the Technical University of Munich (TUM) has built platinum nanoparticles for catalysis in fuel cells: The new size-optimized catalysts are twice as good as the best process commercially available today.

Fuel cells may well replace batteries as the power source for electric cars. They consume hydrogen, a gas which could be produced for example using surplus...

Im Focus: The secret of mushroom colors

Mushrooms: Darker fruiting bodies in cold climates

The fly agaric with its red hat is perhaps the most evocative of the diverse and variously colored mushroom species. Hitherto, the purpose of these colors was...

Im Focus: First results of the new Alphatrap experiment

Physicists at the Max Planck Institute for Nuclear Physics in Heidelberg report the first result of the new Alphatrap experiment. They measured the bound-electron g-factor of highly charged (boron-like) argon ions with unprecedented precision of 9 digits. In comparison with a new highly accurate quantum electrodynamic calculation they found an excellent agreement on a level of 7 digits. This paves the way for sensitive tests of QED in strong fields like precision measurements of the fine structure constant α as well as the detection of possible signatures of new physics. [Physical Review Letters, 27 June 2019]

Quantum electrodynamics (QED) describes the interaction of charged particles with electromagnetic fields and is the most precisely tested physical theory. It...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on UV LED Technologies & Applications – ICULTA 2020 | Call for Abstracts

24.06.2019 | Event News

SEMANTiCS 2019 brings together industry leaders and data scientists in Karlsruhe

29.04.2019 | Event News

Revered mathematicians and computer scientists converge with 200 young researchers in Heidelberg!

17.04.2019 | Event News

 
Latest News

A human liver cell atlas

15.07.2019 | Life Sciences

No more trial-and-error when choosing an electrolyte for metal-air batteries

15.07.2019 | Power and Electrical Engineering

Possibilities of the biosimilar principle of learning are shown for a memristor-based neural network

15.07.2019 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>