An environmentally friendly, efficient and low-cost method for hydrogenation of graphene with visible light has been developed by researchers at Uppsala University and AstraZeneca Gothenburg, Sweden. The research study is presented in an article in Nature Communications.
The study shows that the two-dimensional and atom-thin carbon material graphene reacts with formic acid in a water solution upon irradiation with visible light. In the reaction, formic acid acts as masked hydrogen and a material is produced where hydrogen extensively has been added to graphene. One says that graphene has been hydrogenated. The study was performed by Assoc. Prof. Henrik Ottosson’s research group at the Department of Chemistry – Ångström Laboratory, together with colleagues in Chemistry, Physics and Engineering at Uppsala University and at AstraZeneca Gothenburg.
“The reaction is convenient and cheap, and hydrogenated graphene may be applied within areas such as hydrogen storage. Additionally, upon functionalization of graphene one can open a band gap and this fact is of high relevance for electronics applications”, says Henrik Ottosson.
Yet, graphene research is a side-project in Henrik Ottosson’s group. The group normally studies the behaviours of various aromatic hydrocarbons upon irradiation, and they apply a rule, the so-called Baird’s rule, which can be derived through chemically applied quantum mechanics.
Chemical compounds that are aromatic have an inherently high stability and often they are not easy to degrade. Benzene is the most well known aromatic compound and more than half of all known chemical compounds contain aromatic groups.
The high stability of aromatic compounds is explained by Hückel’s ‘4n+2’ rule, but this rule is only valid for compounds in their electronic ground states. Upon exposure to light of a certain wavelength, the aromatic compounds reach electronically excited states. According to Baird, compounds that are aromatic in the ground state become antiaromatic and reactive in the excited state. The rule, neglected for decades, can now be used to describe various behaviours of aromatic compounds when irradiated.
Using Baird’s rule, Henrik Ottosson’s group develops new light-initiated reactions. First, they studied addition of hydrosilanes to benzenes, naphthalene and gradually larger polycyclic aromatic hydrocarbons (hydrosilanes are compounds that can be regarded as heavy analogues of hydrogen). Despite the fact that it is not possible to explain if, and how, Baird’s rule can be applied to graphene (an essentially infinitely large polycyclic aromatic hydrocarbon), the group explored graphene chemistry and found a very efficient addition reaction when using formic acid.
At AstraZeneca one sees interesting possibilities for the future:
“It has become more common to apply light-initiated reactions during the development of new molecules in our drug research programs. We challenge ourselves to continuously develop more efficient and environmentally friendly chemical methods. The recent progress we have seen in photochemistry, highlighted by the results herein, will increase our opportunities to access chemistry that no one thought possible a few years ago. In addition, graphene based materials have exceptional inherent properties. There is a wealth of possible applications that could result in the next biomedical revolution”, says Joakim Bergman, Innovative Medicines and Early Development Biotech Unit AstraZeneca Gothenburg.
Being able to determine magnetic properties of materials with sub-nanometer precision would greatly simplify development of magnetic nano-structures for future spintronic devices. In an article published in Nature Communications Uppsala physicists make a big step towards this goal – they propose and demonstrate a new measurement method capable to detect magnetism from areas as small as 0.5 nm2.
Due to the ever-growing demand for more powerful electronic devices the next generation spintronic components must have functional units that are only a few nanometers large. It is easier to build a new spintronic device, if we can see it in a sufficient detail. This becomes more and more tricky with the rapid advance of nano-technologies, especially when we need not only an overall picture “how the thing looks”, but also know its physical properties at nano-scale. One of instruments capable of such detailed look is a transmission electron microscope.
Electron microscope is a unique experimental tool offering to scientists and engineers a wealth of information about all kinds of materials. Differently from optical microscopes, it uses electrons to study the materials, and thanks to that it achieves an enormous magnification. For example, in crystals one can even observe individual columns of atoms. Electron microscopes routinely provide information about structure, composition and chemistry of materials. Recently researchers found ways to use electron microscopes also for measuring magnetic properties. There, however, atomic resolution has not been reached so far.
A team of three physicists from Uppsala University – Ján Rusz, Jakob Spiegelberg and Peter Oppeneer, together with colleagues from Nagoya University (Japan) and Forschungszentrum Jülich (Germany) have developed and experimentally proven a new method, which allows to detect magnetism from individual atomic planes. The area of the sample, from which a magnetic signal was detected, is about a trillion (1012) times smaller than that of an average grain of sand.
‘The discovery of this method came from an unexpected result obtained from computer simulations. It was a surprise, which made us dig deeper into it. Thanks to the international collaboration our curious theoretical observation was soon after followed by an experimental confirmation’, says Ján Rusz.
A significant advantage of this new method is its ease of application. Modern transmission electron microscopes can apply the method right away, without any need of modifications or special equipment.
The University of Copenhagen (UCPH) (Danish: Københavns Universitet) is the oldest and second largest university and research institution in Denmark.
Founded in 1479 as a studium generale, it is the second oldest institution for higher education in Scandinavia after Uppsala University (1477). The university has more than 37,000 students, and more than 7,000 employees. The university has several campuses located in and around Copenhagen, with the oldest located in central Copenhagen. Most courses are taught in Danish; however, many courses are also offered in English and a few in German. The university has 2,800 foreign students of which about half are from Nordic countries.
The university is a member of the International Alliance of Research Universities (IARU), along with University of Cambridge, University of Oxford, Yale University, The Australian National University, and UC Berkeley, amongst others. The Academic Ranking of World Universities, compiled by Shanghai Jiao Tong University, sees Copenhagen as the leading university in Scandinavia and the 40th ranked university in the world in 2010. It is also ranked 52nd in the 2011 QS World University Rankings. Moreover, In 2013, according to the University Ranking by Academic Performance, the University of Copenhagen is the best university in Denmark and 25th university in the world. The university has had 8 alumni become Nobel laureates and 1 Turing Award recipient.
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University of Copenhagen research articles from Innovation Toronto
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Uppsala University (Swedish: Uppsala universitet) is a research university in Uppsala, Sweden, and is the oldest university in Sweden, founded in 1477.
It ranks among the best universities in Northern Europe in international rankings.
The university rose to pronounced significance during the rise of Sweden as a great power at the end of the 16th century and was then given a relative financial stability with the large donation of King Gustavus Adolphus in the early 17th century. Uppsala also has an important historical place in Swedish national culture, identity and for the Swedish establishment: in historiography, literature, politics, and music. Many aspects of Swedish academic culture in general, such as the white student cap, originated in Uppsala. It shares some peculiarities, such as the student nation system, with Lund University and the University of Helsinki.
Uppsala belongs to the Coimbra Group of European universities. The university has nine faculties distributed over three “disciplinary domains”. It has about 23,000 full-time students, and about 2,400 doctoral students. It has a teaching staff of roughly 4,000 (part-time and full-time) out of a total of 6,200 employees. Twenty-four percent of the 575 professors at the university are women. Of its turnover of 5.5 billion SEK (approx. 850 million USD) in 2012, 29% went to education on basic and advanced level, while 67% went to research and research programs.
Architecturally, Uppsala University has traditionally had a strong presence in the area around the cathedral on the western side of the River Fyris. Despite some more contemporary building developments further away from the centre, Uppsala’s historic centre continues to be dominated by the presence of the university.
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Uppsala University research articles from Innovation Toronto
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