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 One step closer to reality
20.04.2018 | Max-Planck-Institut für Entwicklungsbiologie

nachricht The dark side of cichlid fish: from cannibal to caregiver
20.04.2018 | Veterinärmedizinische Universität Wien

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Spider silk key to new bone-fixing composite

University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.

Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.

Im Focus: Writing and deleting magnets with lasers

Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.

Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...

Im Focus: Gamma-ray flashes from plasma filaments

Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.

The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...

Im Focus: Basel researchers succeed in cultivating cartilage from stem cells

Stable joint cartilage can be produced from adult stem cells originating from bone marrow. This is made possible by inducing specific molecular processes occurring during embryonic cartilage formation, as researchers from the University and University Hospital of Basel report in the scientific journal PNAS.

Certain mesenchymal stem/stromal cells from the bone marrow of adults are considered extremely promising for skeletal tissue regeneration. These adult stem...

Im Focus: Like a wedge in a hinge

Researchers lay groundwork to tailor drugs for new targets in cancer therapy

In the fight against cancer, scientists are developing new drugs to hit tumor cells at so far unused weak points. Such a “sore spot” is the protein complex...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

IWOLIA: A conference bringing together German Industrie 4.0 and French Industrie du Futur

09.04.2018 | Event News

 
Latest News

Magnetic nano-imaging on a table top

20.04.2018 | Physics and Astronomy

Start of work for the world's largest electric truck

20.04.2018 | Interdisciplinary Research

Atoms may hum a tune from grand cosmic symphony

20.04.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>