Graphene Quantum Dots: Introduction and Market News - Page 6

Dotz Nano, a nanotechnology company focused on the development, manufacture and commercialization of graphene quantum dots (GQDs), has signed a marketing agreement with Strem Chemicals, a manufacturer and distributor of specialty chemicals headquartered in the U.S.

Strem Chemicals will aim to facilitate sales of Dotz’s GQDs to academic, industrial and government research and development laboratories, as well as commercial businesses using GQDs for research purposes.

Researchers at Rice University have found that nitrogen-doped graphene quantum dots (NGQDs) could be an efficient electrocatalyst for making complex hydrocarbons from carbon dioxide, and used electrocatalysis to demonstrated the conversion of the greenhouse gas into small batches of ethylene and ethanol. This could prove a fascinating and simple way to recycle waste carbon dioxide into valuable fuel.

While the researchers say that the exact mechanism is yet to be fully explored, they found that NGQDs worked nearly as efficiently as copper, which is also being tested as a catalyst to reduce carbon dioxide into liquid fuels and chemicals. In lab tests, NGQDs proved able to reduce carbon dioxide by up to 90% and convert 45% into either ethylene or alcohol, comparable to copper electrocatalysts. NGQDs also have the advantage of keeping their catalytic activity for a long time.

Israel-based graphene quantum-dots (GQD) developer Dotz Nano has successfully concluded its IPO and is now listed in the Australian stock exchange under the ticker ASX:DTZ.

The IPO was very successful - Dotz Nano raised $6 million AUD and the shares doubled in the first day of trading. Following the IPO, Dotz Nano signed a memorandum of understanding with Nanyang Technological University, Singapore (NTU Singapore) to establish a graphene quantum dots application research center.

A collaborative project involving scientists from TU Wien (Vienna, Austria), RWTH Aachen (Germany) and the University of Manchester (UK) has created an artificial atom in graphene that opens up possibilities for quantum computing, as their properties can be directly tuned.

Artificial atoms can be viewed as prisons for electrons; Under such confining conditions, electrons often exhibit properties different from their usual characteristics. But like their counterparts in regular atoms, electrons in these structures (also called quantum dots) can also be made to occupy discrete quantum states. "In most materials, electrons may occupy two different quantum states at a given energy. The high symmetry of the graphene lattice allows for four different quantum states. This opens up new pathways for quantum information processing and storage" explains a researchers from TU Wien. However, creating well-controlled artificial atoms in graphene turned out to be extremely challenging.

Researchers at Australia's Griffith University have discovered a fascinating mechanism, that may allow the design of a new class of composite materials for light harvesting and optoelectronics. The team has found a quantum-confined bandgap narrowing mechanism, where UV absorption of the graphene quantum dots and TiO2 nanoparticles can easily be extended into the visible light range.

According to the scientists, real life application of this would be high efficiency paintable solar cells and water purification using sun light. In addition, the team states that "this mechanism can be extremely significant for light harvesting. What's more important is we've come up with an easy way to achieve that, to make a UV absorbing material to become a visible light absorber by narrowing the bandgap."

Researchers from KAUST have found that graphene quantum dots could expand the usable spectral region of light in silicon solar cells to boost their efficiency and provide a more cost-effective way for energy production.

Graphene quantum dots are small flakes of graphene that are useful because of their interaction with light. One of these interactions is optical downconversion, which is a process that transforms light of high energies into lower energy (for example, from the ultraviolet to the visible). Silicon absorbs light very efficiently in the visible part of the spectrum, and therefore appears black. However, the absorption strength of silicon for ultraviolet light is much smaller, meaning that less of this light is absorbed, reducing the efficiency of solar cells in that part of the spectrum. One way around t this problem is the downconversion of ultraviolet light to energies where silicon is a more efficient absorber.

Fuji Pigment recently announced the development of a large-scale manufacturing process for carbon and graphene quantum dots (QDs). QDs are usually made of semiconductor materials that are expensive and toxic, especially Cd, Se, and Pb. Fuji Pigment stated that its toxic-metal-free QDs exhibit a high light-emitting quantum efficiency and stability comparable to the toxic metal-based quantum dots.

Quantum yield of the carbon QDs currently exceeds 45%, and the company said it is still pursuing higher quantum efficiency. Quantum yield of the graphene quantum dot is over 80%. QD’s ability to precisely convert and tune a spectrum of light makes them ideal for TV displays, smartphones, tablet displays, LEDs, medical experimental imaging, bioimaging, solar cells, security tags, quantum dot lasers, photonic crystal materials, transistors, thermoelectric materials, various type of sensors and quantum dot computers.

Researchers from Korea Advanced Institute of Science and Technology (KAIST) have fabricated light-emitting diodes (LEDs) based on graphene quantum dots (GQDs). The researchers made pure GQDs using a cost-effective, scalable and environmentally friendly method that allows direct fabrication of GQDs using water, without surfactants or chemical solvents.

Those GQDs were then used as emitter material to create an OLED device.The scientists constructed GQD LEDs exhibiting luminance of 1000 cd/m2, which is well over the typical brightness levels of the portable displays used in smartphones.

Scientists at the University of Illinois at Chicago engineered a humidity sensor on a bacterial spore. They call it NERD, for Nano-Electro-Robotic Device. They've taken a spore from a bacteria and put graphene quantum dots on its surface, then attached two electrodes on either side of the spore. Then they change the humidity around the spore,causing the spore to shrink. As it shrinks, the quantum dots come closer together, increasing their conductivity, as measured by the electrodes.

The researchers report a very sharp reaction once the humidity is changed, around 10 times faster than a sensor made with the most advanced man-made water-absorbing polymers. There was also better sensitivity in extreme low-pressure, low-humidity situations. The researchers also said it is possible to go all the way down to a vacuum and see a response, which is important in applications where humidity must be kept low,like preventing corrosion or food spoilage and space applications, where any change in humidity could signal a leak.

Back in 2013, Rice scientists developed a simple method to reduce coal into graphene quantum dots (GQDs). Now, these Rice researchers have found a way to engineer these GQDs for specific semiconducting properties in two separate processes.

The researchers' work demonstrates precise control over the graphene oxide dots' band gap, the very property that makes them semiconductors. By sorting the QDs through ultrafiltration, it was found possible to produce quantum dots with specific semiconducting properties. The second process involved direct control of the reaction temperature in the oxidation process that reduced coal to quantum dots. The researchers found hotter temperatures produced smaller dots that had different semiconducting properties. The dots in these experiments came from treatment of anthracite, a kind of coal. The processes produce batches in specific sizes between 4.5 and 70 nanometers in diameter.