July 2011

Researchers at the University of California at Los Angeles have developed a new memory device based on Graphene. This is a ferroelectric-field-effect-transistor (FFET) in which graphene is used to write and read the electric dipole moments of an underlying ferroelectric material.

This graphene-FFET has a high fidelity and low operating voltage. Future work will focus on improving the speed of the device's performance.

Northern Graphite Corporation announced that they managed to produce graphene on a test basis using large flake graphite from the Company's Bissett Creek project in Northern Ontario. The company says that their large flake graphite was evaluated as a source material for making graphene by an eminent professor in the field at the Chinese Academy of Sciences who is doing research making graphene sheets larger than 30cm2 in size using the graphene oxide methodology.

The tests indicated that graphene made from Northern's jumbo flake is superior to Chinese powder and large flake graphite in terms of size, higher electrical conductivity, lower resistance and greater transparency.

Researchers from the Rensselaer Polytechnic Institute developed a new way to harvest energy from flowing water using graphene. This could lead the way towards self-powered microsensors used for oil exploration. The team demonstrated the harvesting of 85 nanowatts of power from a sheet of graphene measuring .03 millimeters by .015 millimeters.

It is the first research paper to result from the $1 million grant awarded in 2010 by the Advanced Energy Consortium.

Researchers from the US Department of Energy's Oak Ridge National Laboratory that graphene grains shape and size are controlled by hydrogen and not only by carbon. The team developed a method to grow graphene grains that has perfect hexagonal shapes.

Up until now hyrogen was thought to play a passive role in the process of making graphene - but the new research shows that it has a crucial role.

Researchers from Stanford developed a new cathode material for rechargeable lithium-sulfur batteries - by wrapping sulfur particles in graphene sheets. This new cathode enables batteries with a significantly higher energy density than is currently possible. Such batteries can be used to power electric cars.

Current electric-car batteries 'weak spot' is the cathode materials that have low capacity (about 150 mAh/g for layer oxides and 170 mAh/g for LiFe-PO4). A sulfur cathode has a theoretical specific capacity of 1672 mAh/g - but sulfur is a poor conductor, it expands during discharge, and the polysulfides dissolve in electrolyte. Using graphene to wrap the sulfur may overcome many of these issues.

Andre Geim from the University of Manchester UK (the 2010 Nobel prize in Physics winner) gives a great lecture on Graphene - starting with an introduction and then giving updates from their latest research:

Researchers from Seoul's National University developed a transparent and lightweight speaker made from Graphene. This may enable speakers embedded in windows or displays. It may be especially suited to develop noise-cancelling devices.

The graphene speaker was made by depositing graphene-oxide onto poly vinylidene fluoride (or PVDF) and then reducing it to create a graphene film (this is actually a new method to develop graphene films). So basically this speaker is made from PVDF sandwiched between two graphene electrodes. When an electrical current (from the sound source) is applied, the converse piezoelectric effect causes the PDVF film to distort - and thus sound waves are created.

Scientists from the National Physical Laboratory in New Delhi, India developed graphene based quantum dots (GQDs) blended with organic polymers that can be used in new photovoltaics (solar) cells. This may solve the problem of toxic metals (cadmium and lead) used in today's quantum dots, and the new material is also more stable then current organic materials.

The GQDs are 9-nm in size have similar electronic properties to normal QDs, and actually perform better (less current loss and improved efficiency) because of graphene's high charge carrier mobility. This work could lead to light-weight, flexible and cheap panels - used in large-area roll-to-roll manufacturing. In fact they say that these GQDs may also be used in other applications such as OLED displays, and indeed the team fabricated OLEDs using the new material - with "good performance".

Stacking several separate layers of graphene is useful for several applications, such as supercapacitors. But stacked graphene forms a graphite-like mass, which makes it less useful. Researchers from Monash University in Australia discovered that keeping graphene wet can keep it from stacking.

The team got their idea from examining Graphene Paper - which is made by filter graphene suspended in water. The water acts as a spacer between the individual graphene layers.