Graphene-Info is the web's leading resource on graphene technology
Graphene is a one-atom-thick material with exciting potential and applications. We bring you daily news and resources on this exciting new technology!
Recent Graphene news:
Korean researchers have developed a new blue nitride LED that uses 3D graphene foam as a transparent conductor for the p-contact. They say that the graphene foam reduced the forward voltage by 26% and increased the light output by 14%.
The researchers used commercial 3D graphene foam, produced on 3D copper foam using chemical vapor deposition. The graphene foam on copper was then spin-coated with PMMA and the copper etched away (using ammonium sulfate). The graphene foam was cut into a square and transferred to the p-type gallium nitride layer of a commercial blue LED.
A worldwide team of researchers (from the US and Japan) managed to observe Hofstadter’s butterfly fractal pattern for the first time. This pattern was predicted by Douglas Hofstadter back in 1976 - and it emerges when electrons are confined to a two-dimensional sheet, and subjected to both a periodic potential energy and a strong magnetic field.
To create the periodic potential energy, the researchers used an effect called a moiré pattern that arises naturally when graphene is placed on a flat boron nitride substrate. Mapping the graphene energy spectrum (by measuring the electronic conductivity of the samples at very low temperatures in extremely strong magnetic fields, up to 35 Tesla) showed the predicted fractal pattern. The actual mapping can be seen below:
Researchers from the National Physical Laboratory (the NPL) and the University of Cambridge wants to redefine the ampere, using the world's first graphene single-electron pump (SEP).
The idea is to redefine the ampere in terms of the electron charge. The SEP creates a flow of individual electrons by shutting them in a quantum dot and then emitting them one at a time at a well-defined rate. The researchers managed to produce such a pump for the first time, and this can provide the speed of electron flow - which can be used to redefine the ampere.
Graphene based sensors are made from an insulating layer coated with a graphene sheet. A worldwide research team led by the University of Illinois discovered that one can improve the sensitivity of graphene bases sensors by manipulating the chemical properties of the insulating layer used in those sensors.
It is known that a perfect graphene sheet is insensitive to other gas molecules, and it has to have "defects" to make it work. If the insulating layer is also perfect, the device is still not sensitive. But it turns out that a perfect graphene sheet on a insulating layer that has defects is also sensitive. This opens up a new "design space" for sensors - one can control the sensitivity by adding defects either to the graphene layer or the insulating layer.
Researchers from Spain have succeeded in giving graphene magnetic properties - they have basically managed to create a hybrid graphene surface that behaves like a magnet. This may enable graphene-based Spintronic devices.
A magnetic material is a material in which most electrons have the same spin. In order to achieve that, the researchers grew a graphene sheet on a ruthernium single crystal substrate. Then they evaporated TCNQ (tetracyano-p-quinodimethane, which acts as a semiconductor at very low temperatures) molecules on the graphene surface. The TCNQ molecule acquired long-range magnetic order.
California Lithium Battery (CalBattery) were selected as a 2013 TechConnect National Innovation awardee for the development of its breakthrough, very-high specific capacity Lithium-ion silicon-graphene (SiGr) composite anode material. The TechConnect award committee selects the top early-stage innovations from hundreds of technologies from all over the world, and rankings are based on the potential positive impact the technology will have on a specific industry sector.
California Lithium Battery (CalBattery) recently signed a licensing agreement with the US Department of Energy’s Argonne National Laboratory to commercialize their silicon-graphene composite anode material (called GEN3). CalBattery and Argonne has been working together for over a year under a Work for Others agreement to develop this technology. Back in October 2012 CalBattery said that in independent full cell tests, the material shows unrivaled performance characteristics.
Sweden's Department of Energy and Environment studied the available information on graphene, and came up with the conclusion that the new material may have potentially adverse environmental and health risks. Graphene could exert a considerable toxicity and tt is also suggested that graphene is both persistent and hydrophobic (graphene is a very effective water repellent).
There are still many risk-related knowledge gaps to be filled, according to the researchers as "Considerable" emissions of graphene from electronic devices and composites are possible in the future.