Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

How the first step affects the (watery) result

24.06.2010
German Scientists from Jena and Erlangen-Nürnberg show the way to a more effective creation of hydrogen

Energy from hydrogen – scientists from all over the world work on this solution to overcome the energy crisis. Amongst other things they try to use the sunlight as driving force for the splitting of water into hydrogen and oxygen.

In trying to copy the photosynthesis in the laboratory a team of scientists of the Universities of Jena and Erlangen-Nürnberg and of the Institute of Photonic Technology (IPHT) in Jena (Germany) made a huge step forward. The physiccists and chemists were able to prove in their tests, that the first step already affects the efficiency of hydrogen generation.

“This is as if you would decide about where you´re going to by turning the ignition key in the car,” says PD Dr Michael Schmitt from the Institute of Physical Chemistry (IPC) of the University of Jena. To put it scientifically: “The Franck-Cordon-point has to be created in such a way that the initial process of transferring electrons already points into the direction of the catalytic active centre.“ The results were published in the science journal „Angewandte Chemie Int. Ed.“.

In their tests for a more efficient energy conversion the scientists focus on chemical photo catalysts. With this light is being used to let electrons “jump“ well-directed from one subunit of the molecule to the other or to transport them over a ligand, which is a “bridge“.

Like the photosynthesis this process, which the chemists run in the laboratory, works in two main steps: A special metal complex with Ruthenium as its main component serves as an antenna which harvests the light. The Ruthenium then transfers an electron onto the reaction centre. The core of the reaction centre is a Palladium atom. At this metal centre the hydrogen is finally generated. But other than in nature not all electrons reach the palladium centre from the Ruthenium in the laboratory construction. Some choose “detours“, some enter “roundabouts“ or “blind alleys“ and thus are being lost for the reaction. “Supported by resonance Raman spectroscopy we were able to watch and see where the electron ends after directly after the photoexitation,“ describes Prof Dr Juergen Popp, director of IPC and IPHT. „Thereby we were able to develop a new synthesis paradigm“, Michael Schmitt adds. The team of scientists could prove that the efficiency of hydrogen generation depends on the light wavelength. It is more efficient the redder the light used for photo excitation is – light of a wavelength of 550 nm is ideal. “The redder the light the more electrons are transferred to the ligand, that connects the Ruthenium with the Palladium“, Schmitt says. Moreover the initial absorption step decides where the electron goes and thus how effective the generation of energy is.

“This knowledge enables us to put up well-directed barriers so that the electrons don´t take a ,wrong turn’ but exclusively end up at the Palladium“, says Prof Popp explaining the application potential of this fundamental research. In the laboratory the hydrogen generation is four times above former data but still far below the necessary rate. Now it is up to the chemists, like the participating Prof. Dr Sven Rau, to optimize the molecular catalysts, that “no electrons will be taken on by terminal ligands,“ as Schmitt explains.

The scientists know that it is still a long way to go to copy the photosynthesis of nature correctly and efficiently. “But due to our spectroscopic analysis we took a huge step on this way“, Prof Popp is sure though.

Original Publication:
Stefanie Tschierlei, Michael Karnahl, Martin Presselt, Benjamin Dietzek, Julien Guthmuller, Leticia González, Michael Schmitt, Sven Rau und Jürgen Popp: „Photochemisches Schicksal:„Photochemical Fate: The First Step Determines Efficiency of H2 Formation with a Supramolecular Photocatalyst“, Angew. Chem. Int. Ed. 2010, 122, 3981-3984.
Contact:
Prof. Dr. Jürgen Popp / PD Dr. Michael Schmitt
Institute of Physical Chemistry of Jena University
Helmholtzweg 4
D-07743 Jena
Phone: +049 (0)3641 / 948320 or 948367
Email: juergen.popp[at]uni-jena.de / m.schmitt[at]uni-jena.de

Axel Burchardt | idw
Further information:
http://www.uni-jena.de/en/start_en.html

Further reports about: CHEMISTRY IPC IPHT Palladium Ruthenium hydrogen generation

More articles from Life Sciences:

nachricht Clock stars: Astrocytes keep time for brain, behavior
27.03.2017 | Washington University in St. Louis

nachricht Cryo-electron microscopy achieves unprecedented resolution using new computational methods
24.03.2017 | DOE/Lawrence Berkeley National Laboratory

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Electrical 'switch' in brain's capillary network monitors activity and controls blood flow

27.03.2017 | Health and Medicine

Clock stars: Astrocytes keep time for brain, behavior

27.03.2017 | Life Sciences

Sun's impact on climate change quantified for first time

27.03.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>