July 2010

Researchers from Shanghai University has developed two water-based dispersible graphene derivatives that can effectively inhibit the growth of E.coli and have minimal toxic effects on harming cells (cytotoxicity). The two derivatives are based on graphene oxide (GO) and reduced graphene oxide (rGO).

The group tested the antibacterial properties of the GO sheets with E.coli DH5 cells via a luciferase-based ATP assay kit. After two hours incubation with the GO sheets of 20 µg/mL at 37C, the cell metabolic activity of the bacteria fell to around 70 per cent. With a GO concentration of 85 µg/mL, the activity of the E.coli cells fell to just 13 per cent suggesting a strong inhibition ability of GO nanosheets to E.coli, said the researchers.

Researchers from the University of Southern California is using Graphene as a transparent flexible conductive layer for organic solar cells (OPVs). OPVs are considered as a cheap way to make solar cells, because they are easy to make, they weight very little and can be flexible. The USC team has produced graphene/polymer sheets ranging in sizes up to 150 square centimeters that in turn can be used to create dense arrays of flexible OPV cells.

Graphene marks a major advance over another OPV design, one based on Indium-Tin-Oxide (ITO) in at least one crucial area: the ITO cells fails at a very small angle of bending, while the graphene based cells remained operational and sustained repeated bending with more than twice the stress angle of the ITO solar cells.

Vorbeck MaterialsVorbeck Materials Corp will collaborate with the Pacific Northwest National Laboratory (PNNL) in a R&D agreement (CRADA) to develop Li-ion battery electrodes using Vorbeck's unique graphene material, Vor-x(TM). These new battery materials could enable electronic devices and power tools that recharge in minutes rather than hours or function as part of a hybrid battery system to extend the range of electric vehicles.

PNNL has demonstrated that small quantities of high-quality graphene can dramatically improve the power and cycling stability of Li-ion batteries, while maintaining high-energy storage capacities. This advance can lead to batteries that both store large amounts of energy and recharge quickly.

Korean researchers have made a new type of composite material made from reduced graphene oxide and magnetite that could effectively remove arsenic from drinking water. Arsenic is one of the most carcinogenic elements known and its presence in drinking water is a huge problem in many areas of South Asia and the western United States. Arsenic is usually removed using bare magnetite, but adding graphene makes it much more efficient.

The new magnetite composite was used to remove over 99.9% of arsenic in a sample. The composite can be dispersed in water, and then removed after it has absorbed the arsenic (by using a permanent hand-held magnet).

Korean-based Hanwha group has agreed to give 1$ million in funding to XG Sciences, a Michigan State University spinoff working on Graphene Nanoplatelets. The key to the material's capabilities is a fast and inexpensive process for separating layers of graphene into stacks less than 10 nanometers in thickness but with lateral dimensions anywhere from 100 nm to several microns, coupled with the ability to tailor the particle surface chemistry to make it compatible with water, resin or plastic systems.

Adding xGnP® graphene nanoplatelets to polymers at low concentrations results in nanocomposites that are multifunctional in that they possess an array of enhanced properties—including improved strength and significantly increased electrical and thermal conductivity—leading to new and expanded applications.

A group of scientists from Germany, China and the US has created a Graphene-based transistor composed of 13 benzene rings. This molecule (called Coronene) shows an improved electronic band gap, a property which may help to overcome one of the central obstacles to applying graphene technology for electronics.

The team's new approach to make graphene is bottom up—building up the graphene, molecular piece by piece. To do this, Tao relies on the chemical synthesis of benzene rings, hexagonal structures, each formed from 6 carbon atoms. "Benzene is usually an insulating material, " Tao says. But as more such rings are joined together, the material's behavior becomes more like a semiconductor.