Reduced graphene oxide: an introduction - Page 5

Researchers at the Department of Energy’s Lawrence Berkeley National Laboratory have developed a mix of metal nanocrystals wrapped in graphene that may open the door to the creation of a new type of fuel cell by enabling enhanced hydrogen storage properties.

ultrathin oxide layer (oxygen atoms shown in red) coating graphene-wrapped magnesium nanoparticles (orange) still allows in hydrogen atoms (blue) for hydrogen storage applications

The team studied how graphene can be used as both selective shielding, as well as a performance increasing factor in terms of hydrogen storage. The study drew upon a range of Lab expertise and capabilities to synthesize and coat the magnesium crystals, which measure only 3-4 nanometers (billionths of a meter) across; study their nanoscale chemical composition with X-rays; and develop computer simulations and supporting theories to better understand how the crystals and their carbon coating function together.

Researchers at the UAE-based Masdar Institute, part of the Khalifa University of Science and Technology, have announced significant progress in their research in the field of optimized graphene-based membranes, which aim to make water filtration and desalination more efficient and sustainable.

The team worked to develop membranes made of layered reduced graphene-oxide sheets that are able to block the passage of salt ions in a membrane-based seawater desalination process. The spacing between the sheets is what ultimately affects the membrane’s efficacy, or its ability to filter impurities like salt ions while still permitting water molecules to pass through. The spaces between sheets must be just right if they are too large and salt ions are not filtered out, and if they too small and even water molecules are unable to penetrate the membrane.

Researchers from Tsinghua University in China have designed a low-cost energy storage device using a TiO2-assisted UV reduction of sandwiched graphene components. The sandwich structure consists of two active layers of reduced graphene oxide hybridized with TiO2, with a graphene oxide separator (rGO-TiO2/rGO/rGO-TiO2). In the device, the separator layer also acts as a reservoir for the electrolyte, which affects ion diffusion—a known problem for layered membrane devices—and affects both the capacity and rate performance.

The team explained that a step-by-step vacuum filtration process is used to form the membrane structure, and the amount of graphene oxide used in the filtration solutions can be adjusted to precisely tune the thickness of each layer. Irradiation of the dried membrane with UV light then reduces the graphene oxide to rGO with assistance from the TiO2.

Rutgers University scientists have created a graphene-based sensor that could lead to earlier detection of asthma attacks and improve the management respiratory diseases, possibly preventing hospitalizations and deaths.

The Rutgers team aims for the sensor to pave the way for the development of devices - possibly resembling fitness trackers - which people could wear and then know when and at what dosage to take their medication.

Nippon Shokubai, a Japan-based global materials provider, has announced its success in mass production tests of graphene oxide-based materials. The production volume attained in the mass production test was reportedly improved dozens of times as much as that attained at laboratory, and Nippon Shokubai will start to provide graphene oxide-based materials as samples for application development.

The graphene oxide-based materials are lamellar carbon compounds with the approximately 1nm thickness and the company expects them to be suitable for various functional materials, such as lubricants, water treatment membranes, and catalysts. Nippon Shokubai stated that it has resolved various problems relating to chemical reactions of the production process and succeeded in the mass production test by utilizing its control technology for stable proceeding of chemical reactions in collaboration with Okayama University which retained academic knowledge about reaction mechanism of graphene oxide.

A team of scientists at Washington University has developed a technique for using sheets of graphene oxide to obtain drinkable water using sunlight; The technique involves heating dirty water to a boil - creating purified steam that can be collected and safely consumed.

The team has devised a method of heat localization using bilayered biofoam composed of bacterial nanocellulose (BNC) and reduced graphene oxide (RGO). The bilayer structure was created by growing Gluconacetobacter hansenii bacteria in the presence of graphene oxide flakes.

A team of researchers from Italy has created hybrid perovskite-graphene solar cells that show good stability upon exposure to sunlight, while still maintaining an impressive efficiency of over 18% - the highest reported efficiency of graphene perovskite hybrid solar cells to date.

Despite tremendous progress in Perovskite PV performance, the stability of these devices is still questionable. In particular, air and humidity degrade cell performance, as do continued exposure to sunlight and heat, setting back the advantages over other types of solar cells. Graphene and graphene-related materials (GRMs) have properties that make them shine in applications like protective layers, and so arise as natural candidates to protect PSCs from atmospheric degradation.

Researchers at North Carolina State University have developed a technique that enables the integration of graphene, graphene oxide (GO) and reduced graphene oxide (rGO) onto silicon substrates at room temperature by using nanosecond pulsed laser annealing. The advance may open the door to the possibility of creating new electronic devices, such as smart biomedical sensors.

In this new technique, the researchers start with a silicon substrate. They top that with a layer of single-crystal titanium nitride, using domain matching epitaxy to ensure the crystalline structure of the titanium nitride is aligned with the structure of the silicon. They then place a layer of copper-carbon alloy on top of the titanium nitride, again using domain matching epitaxy. Finally, the researchers melt the surface of the alloy with nanosecond laser pulses, which pulls carbon to the surface.

Researchers at Korea Advanced Institute of Science and Technology (KAIST) have developed a new graphene oxide-based speaker design said to be specifically targeted for the mobile audio market. The speaker does not require an acoustic box to produce sound.

The researchers used graphene in a relatively simple, two-step process that yielded a thermoacoustic speaker. Thermoacoustics is based on the idea that sound can be produced by the rapid heating and cooling of a material instead of through vibrations.

Researchers at the University of Maryland have developed a method to 3D print heating elements. The created heating elements could be very small and at the same time they can create high temperatures.

Heating elements may have various uses, like ones for chemical reactions that often need some sort of heating to work. For this purpose it was common to use a laser to create high temperatures at a small scale, but it is very expensive and doesn’t provide a consistent temperature. This is why researchers decided to develop a new technique to 3D print very small heating elements.