Navigation Links
Toward a more efficient use of solar energy
Date:4/14/2011

This release is available in German.

The exploitation and utilization of new energy sources are considered to be among today's major challenges. Solar energy plays a central role, and its direct conversion into chemical energy, for example hydrogen generation by water splitting, is one of its interesting variants. Titanium oxide-based photocatalysis is the presently most efficient, yet little understood conversion process. In cooperation with colleagues from Germany and abroad, scientists of the KIT Institute for Functional Interfaces (IFG) have studied the basic mechanisms of photochemistry by the example of titania and have presented new detailed findings.

Even though hydrogen production from water and sunlight by means of oxide powders has been studied extensively for several decades, the basic physical and chemical mechanisms of the processes involved cannot yet be described in a satisfactory way. Together with colleagues from the universities of St. Andrews (Scotland) and Bochum and Helmholtz-Forschungszentrum Berlin, scientists at KIT's Institute for Functional Interfaces, headed by Professor Christof Wll, have succeeded in gathering new findings on the fundamental mechanisms of photochemistry on titanium dioxide (TiO2).

Titanium dioxide, or titania, is a photoactive material occurring in nature in the rutile and anatase modifications, the latter of which being characterized by a ten times higher photochemical activity. When the white TiO2 powder, which is also used as a pigment in paints and sunscreens, is exposed to light, electrons are excited and can, for example, split water into its components oxygen and hydrogen. The hydrogen produced in that way is a "clean" energy source: No climate-killing greenhouse gases are generated but only water is produced during combustion. Titanium dioxide is also used to manufacture self-cleaning surfaces from which unwanted films are removed through photochemical processes triggered by incident sunlight. In hospitals, this effect is used for sterilizing specially coated instruments by means of UV irradiation.

So far, the physical mechanisms of these photochemical reactions on titania surfaces and especially the reason for the much higher activity of anatase could not be explained. The powder particles used in photoreactors are as tiny as a few nanometers only and are thus too small for use in studies by means of the powerful methods of surface analysis. By using instead mm-sized single-crystal substrates, the researchers were for the first time able to precisely study photochemical processes on the surface of titanium dioxide by means of a novel infrared spectrometer.

Using a laser-based technique, the scientists, in addition, determined the lifetime of light-induced electronic excitations inside the TiO2 crystals. According to Professor Christof Wll, Head of the IFG, exact information about these processes is of great importance: "A short lifetime means that the excited electrons fall back again at once: We witness some kind of an internal short circuit. In the case of a long lifetime, the electrons remain in the excited state long enough to be able to reach the surface of the crystal and to induce chemical processes." Anatase is particularly well suited for the latter purpose because it is provided with a special electronic structure that prevents "internal short circuits". Knowledge of this feature will allow the researchers to further optimize shape, size, and doping of anatase particles used inside photoreactors. The objective is to develop photoactive materials with higher efficiencies and longer lifetimes: "The results obtained by Professor Wll and his co-workers are of great importance regarding the generation of electrical and chemical energy from sunlight, and especially regarding the optimization of photoreactors," says Professor Olaf Deutschmann, spokesman of the Helmholtz Research Training Group on "Energy-related Catalysis".


'/>"/>

Contact: Monika Landgraf
presse@kit.edu
49-721-608-47414
Helmholtz Association of German Research Centres
Source:Eurekalert

Related biology news :

1. Toward a green grid for delivering solar and wind-based electricity
2. Progress toward the clinical application of autologous induced pluripotent stem cells and gene repair therapy for treatment of familial hypercholesterolemia
3. An advance toward blood transfusions that require no typing
4. Its time to take a unified approach toward measuring sustainability
5. Green chemistry offers route towards zero-waste production
6. Researchers working toward automating sedation in intensive care units
7. A nanoscale rope, and another step toward complex nanomaterials that assemble themselves
8. Toward controlling fungus that caused Irish potato famine
9. Big city life may make residents lean toward green, study says
10. Tracing microbes between individuals towards personalized oral health care
11. Towards an efficient, effective and equitable REDD+
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:3/18/2016)... --> --> Competitive Landscape Analysis ... Physical infrastructure and Perimeter Surveillance & Detection Systems ... and the continuing migration crisis in the Middle ... led visiongain to publish this unique report, which is crucial ... & security companies in the border security market and the ...
(Date:3/15/2016)... , March 15, 2016 --> ... published by Transparency Market Research "Digital Door Lock Systems Market ... 2015 - 2023," the global digital door lock systems market ... in 2014 and is forecast to grow at a CAGR ... micro, small and medium enterprises (MSMEs) across the world and ...
(Date:3/14/2016)... NXTD ) ("NXT-ID" or the "Company"), a company ... of a new series of commercials on Time Warner Cable ... .  The commercials will air on Bloomberg TV, Fox Business ... show. --> NXTD ) ("NXT-ID" or the "Company"), ... the airing of a new series of commercials on Time ...
Breaking Biology News(10 mins):
(Date:5/24/2016)... ... May 24, 2016 , ... ... and traumatic injuries, will be accelerated by research at Worcester Polytechnic Institute (WPI) ... of wound healing and tissue regeneration. , The novel method, developed by WPI ...
(Date:5/23/2016)... Antonio, Texas (PRWEB) , ... May 23, 2016 , ... The need for blood donations ... released this week by the South Texas Blood & Tissue Center, blood donations are on ... than 30 years, and they are down 21 percent in South Texas in the last ...
(Date:5/23/2016)... LONDON , May 23, 2016 ... Efficiency by 40% - Frontage Implement a Single Platform ... Quality, Compliance and Traceability Within the Bioanalytical lab Frontage ... the United States and China ... across its laboratory facilities. In addition to serving as the global ...
(Date:5/20/2016)... , ... May 20, 2016 , ... The leading Regenerative ... its most experienced veterinary clients have treated over 100 of their own patients with ... to provide the highest level of care for their patients. , The veterinarians ...
Breaking Biology Technology: