Nanosciences
 |
 |
Research
Collaboration between CENIDE researchers and with external partners again produced a large number of publications and successful projects in 2012 and 2013. The following highlights are therefore just a small selection of CENIDE’s research activities.
One success story shared by the nanoscientists of all disciplines is the Interdisciplinary Center for Analytics on the Nanoscale, or ICAN for short, which has been recognised as a DFG Core Facility. ICAN combines the apparatus, techniques and expertise for nanometre-scale analyses and offers the research groups at the University and cooperating partners the methods of analysis best suited to their samples. One of ICAN’s core areas is the microscopy centre in the NanoEnergieTechnikZentrum (NETZ) on the Duisburg campus.
The following are some selected highlights from the different research groups:
Mechanisms on the nanoscale
The research group of Prof. Rolf Möller developed an extraordinary technique with which to track the motion of single atoms and molecules in real-time. The researchers published in Nature Materials how they analysed individual molecules of the blue pigment Phthalocyanine Blue on a copper surface with a scanning tunnelling microscope. During their analysis they found that the measurement on some areas of the molecule did not remain constant but jumped back and forth. This prompted them to develop the electronics to take the normal surface measurements and also measure all the parameters of this noise: switching rate, switching amplitude and frequency ratio. By transferring them to the processes at molecular level, they were able to observe the movement of the molecule in real-time.
Hitherto unknown effects in equally minute dimensions have been observed by Prof. Michael Horn-von Hoegen and his research group: the two-dimensional material graphene, a single layer of hexagonally arranged carbon atoms, conducts an electric current better than any other material. However, this valuable material wrinkles during the manufacture of particularly high-quality graphene, considerably reducing its conductivity. With the aid of a sophisticated analytical technique used for the first time, the researchers were able to prove that the wrinkles disappear entirely on heating, with no detrimental effects on the material. This finding is invaluable for the superfast computers of tomorrow or for flexible displays.
The combination of electrical and magnetic properties in a system has been the subject of some very successful work by two research groups in particular over the past few years: the team of Prof. Heiko Wende, Prof. Wolfgang Kleemann and Dr. Carolin Schmitz-Antoniak have investigated a composite system of ferrimagnetic and ferroelectrical components which creates an electric potential with a magnetic field. The system becomes interesting for digital data storage because the electric polarisation remains even after the magnetic field has been switched off. The principle should also apply the other way, as the researchers reported in Nature Communications: the direction of magnetisation can be switched and a bit written under an electric potential, i.e. with no current flowing. The memory would therefore only need an extremely small amount of energy.
Prof. Gerd Bacher’s research group were also interested in components that combine electrical, optical and magnetic functionality. His team were able to separately measure two coupling constants that had hitherto been a subject of disagreement among experts and show that one of them changes considerably in nanostructures. The researchers were also able to prove that the nanoribbons used by them exhibit magneto-optical functionality at room temperature.
Nano and life
The work of Prof. Christian Mayer’s research group and partners from Essen University Hospital on nanocapsules as oxygen carriers for an artificial blood substitute has already appeared in seven publications, three of them in 2013 alone. They deal with the development and application of polymer nanocapsules filled with perfluordecalin as a solvent for oxygen. Investigation is now underway as to whether
these dispersions have potential as a synthetic blood substitute. The first animal experiments have already confirmed the essential function, and while some aspects of long-term compatibility still remain to be clarified, the chances of success are good.
Self-organisation of nanostructures is the subject of work in the research group of Prof. Carsten Schmuck. In their publication, classed as a “hot paper” by the journal Angewandte Chemie, the researchers describe how they were able, for the first time, to induce small organic molecules to autonomously form a comparatively large gel – or more simply, to make the transition from liquid to solid. Unlike most of its conventional counterparts, this gel does not consist of long, threadlike molecules but exclusively of small organic monomers. Such switchable supramolecular polymers are very interesting as potential functional materials.
In June 2013 the members of the “nanoGEM” project led by PD Dr. Thomas Kuhlbusch presented the results of their years of research work on the release and effects of nanomaterials. Their major discovery has been that whether and how nanomaterials adversely affect health depends not only on their size but also on their surface structure. The project provides important insights for identification of the relevant properties, which simplifies the necessary risk analysis and assessment and makes it possible to define groups according to specific physical and chemical properties for risk evaluation.
Nano in energy technology
When the NanoEnergieTechnikZentrum (NETZ) opened its doors on the Duisburg campus, it finally gave a physical centre to the collaborative research that has been ongoing at the University for many years on nanomaterials for energy technology applications. This unique facility offers the 120 chemists, physicists and engineers the chance to examine and optimise all stages of the process chain, from nanoparticle synthesis from the gas phase through to the finished component.
The beginning of 2012 also saw the launch of the major EU consortium project “BUONAPART-E” headed by Prof. Einar Kruis. The project, which is receiving 10.4 million euros in funding, sets out to manufacture industry-relevant quantities of high-quality nanoparticles in the most energy efficient and environmentally compatible way possible. The scientists intend to show how such processes can be upscaled for high-quality nanoparticle manufacture by means of parallelisation.
Another area in which very successful research is underway is in exploring materials which convert temperature differences into electric current: five research groups in total, led by Prof. Peter Kratzer, Dr. Gabi Schierning, Prof. Roland Schmechel, Dr. Hartmut Wiggers and Prof. Dietrich Wolf, were able to secure funding for their projects on nanostructured thermoelectrics in the second funding period of the Priority Programme 1386 of the German Research Foundation (DFG). In 2012 Dr. Gabi Schierning together with the Institute for Energy and Environmental Technology (IUTA) and the Gesellschaft für Schweißtechnik International (GSI) received the InnoMateria Award for their thermoelectric generator made of nanostructured silicon.
Batteries that last longer, store more energy and contain less combustible material are just one of the goals of the “NaKoLiA” project of Prof. Christof Schulz, Dr. Hartmut Wiggers and Prof. Angelika Heinzel with the Federal Ministry of Education and Research (BMBF). Their aim is to take the products to market maturity, which is also why the researchers have a very specific set of demands: they want to reduce the weight, size, charging time and cost of lithium-ion batteries while simultaneously increasing the storage capacity – using substances that are not harmful to humans or to the environment. Their material of choice is silicon: it is safe, in adequate supply, and therefore inexpensive. The two research groups are additionally working with partners from the Ruhr University Bochum within the “NanoSiLiKat” project on defining criteria for electrode stability and performance with the aim of developing better materials. Higher-performance lithium-ion batteries are essential for future energy storage requirements and electromobility.
Dr. Philipp Wagener from the research group of Prof. Stephan Barcikowski successfully secured 1.52 million euros in funding from the Federal Ministry of Education and Research (BMBF) for his “INNOKAT” project. The research group he set up is developing heterogeneous catalysts based on particularly pure nanoparticles. These catalysts play a critical role in chemical substance conversion or energy storage in chemical form. Their most important component is the noble metal nanoparticles on which the catalytic reactions occur. The purer the surface of these particles, the more active they are. In parallel to this work the junior researcher’s team is also investigating nickel-based nanoparticles, which could replace the hitherto usual – and extremely expensive – platinum in catalysts.
Catalysis in its homogeneous form is meanwhile the topic of Prof. Jochen Gutmann’s research group: in conjunction with colleagues from the Max-Planck-Institut für Kohlenforschung in Mülheim, the scientists have for the first time developed a method of reusing organic catalysts. The findings of their work have been published in Science: in homogeneous catalysis, a process often used in the pharma industry, for example, both the catalyst substances and the starting substances have the same form, e. g. both dissolved in a liquid. At the end of a reaction this always leaves a mixture of the target product and the catalyst substances. The latter then either remain in the product or require intensive treatment to remove them. The researchers have now for the first time used covalent bonds to bind the catalysts to nylon, which makes it possible to separate them quickly and easily from the product after the reaction and re-use them – without any loss of performance or effect on the product.