Graphene applications: what is graphene used for? - Page 14

Researchers at Sweden's Umeå University, Lund University and Denmark's Aarhus University have reported a new way to synthesize graphene oxide, which has significantly fewer defects compared to materials produced by the most common method. To date, graphene oxide of similarly good quality could only be synthesized by using a rather dangerous method involving extremely toxic fuming nitric acid.

Graphene oxide is often used to produce graphene by removing oxygen. However, if there are holes in graphene oxide, there will also be holes after it is converted to graphene. Therefore, the quality of the graphene oxide is very important. Umeå University's Alexandr Talyzin and his research group have now addressed the issue of how to safely make good graphene oxide. 

Researchers from the Vietnam Academy of Science and Technology, VNU University of Science, Hanoi University of Science and Technology and the Russian Academy of Sciences have developed a biosensor that uses graphene electrodes modified by zinc oxide nanoparticles to measure Hypoxanthine (HXA), a material that can be used as a marker for the freshness of meat. The team demonstrated the sensor’s efficacy on pork meat.

The freshness of animal meat in the food industry is an essential property determining its quality and safety. With advanced technology capable of preserving food for extended periods of time, meat can be shipped around the globe and so there is a vital need for effective testing of its condition. Despite the technological advances keeping meat fresh for as long as possible, certain aging processes are unavoidable. Adenosine triphosphate (ATP) is a molecule produced by breathing and responsible for providing energy to cells. When an animal stops breathing, ATP synthesis also stops, and the existing molecules decompose into acid, diminishing first flavor and then safety. Hypoxanthine (HXA) and xanthine are intermediate steps in this transition. Assessing their prevalence in meat indicates its freshness.

UK-based Graphene Innovations Manchester (GIM) and Space Engine Systems (SES) from Canada have signed a Memorandum of Understanding (MoU) to collaborate in various areas of SES’s Hello series of Aerospace and Space vehicles, focusing on using graphene for hypersonic applications.

GIM is working on the development and commercialization of advanced graphene-based solutions for composites, particularly in Graphene Space Habitat,
and also Type V hydrogen storage tanks. GIM is the largest Tier 1 partner in the Graphene Engineering Innovation Centre (GEIC) at the University of Manchester.

Researchers at the University of Cambridge and the University of Warwick have developed a fully 3D-printed quantum dot/graphene-based aerogel sensor for highly sensitive and real-time recognition of formaldehyde at room temperature. Formaldehyde is a known human carcinogen that is a common indoor air pollutant. However, its real-time and selective recognition from interfering gases has thus far remained challenging, especially for low-power sensors suffering from noise and baseline drift. 

The new sensor uses artificial intelligence techniques to detect formaldehyde in real time at concentrations as low as eight parts per billion, far beyond the sensitivity of most indoor air quality sensors.

Researchers from Kyushu University, Nitto Denko Corporation, Tokyo Institute of Technology, Osaka University, National Institute of Advanced Industrial Science and Technology (AIST) and Samsung Electronics have developed a tape that can be used to stick 2D materials to many different surfaces, in an easy and user-friendly way. 

Transfer process of monolayer graphene from Cu(111)/sapphire to a SiO2/Si substrate using the UV tape. Image from Nature Electronics

“Transferring 2D materials is typically a very technical and complex process; the material can easily tear, or become contaminated, which significantly degrades its unique properties,” says lead author, Professor Hiroki Ago of Kyushu University's Global Innovation Center. “Our tape offers a quick and simple alternative, and reduces damage.”

Traditional microelectronic architectures are currently used to power everything from advanced computers to everyday devices. However, scientists are always on the lookout for better technologies. Recently, Los Alamos National Laboratory scientists and their collaborators from Menlo Systems and Sandia National Laboratories, have designed and fabricated asymmetric, nano-sized gold structures on an atomically thin layer of graphene. The gold structures are dubbed “nanoantennas” based on the way they capture and focus light waves, forming optical “hot spots” that excite the electrons within the graphene. Only the graphene electrons very near the hot spots are excited, with the rest of the graphene remaining much less excited.

Illustration of an optoelectronic metasurface consisting of symmetry-broken gold nanoantennas on graphene. Image from Nature

The team adopted a teardrop shape of gold nanoantennas, where the breaking of inversion symmetry defines a directionality along the structure. The hot spots are located only at the sharp tips of the nanoantennas, leading to a pathway on which the excited hot electrons flow with net directionality — a charge current, controllable and tunable at the nanometer scale by exciting different combinations of hot spots. 

Researchers from Germany's Max Planck Institute for Polymer Research and China's Southeast University have reported a graphene-based aqueous memristive device with long-term and tunable memory, regulated by reversible voltage-induced interfacial acid-base equilibria enabled by selective proton permeation through the graphene. 

Memristive devices, electrical elements whose resistance depends on the history of applied electrical signals, are leading candidates for future data storage and neuromorphic computing. Memristive devices typically rely on solid-state technology, while aqueous memristive devices are crucial for biology-related applications such as next-generation brain-machine interfaces. Recently, nanofluidic devices have been reported in which solvated ion transport exhibits memristive behavior. The challenge associated with these approaches is the complexity of the device fabrication. Realizing memristive behavior in a simple system is highly desirable.

Scientists at the University of California San Diego have developed an ultra-sensitive graphene-based sensor that can detect extraordinarily low concentrations of lead ions in water. The device achieved a record limit of detection of lead down to the femtomolar range, which is said to be a million times more sensitive than previous sensing technologies.

The device in this study consisted of a single layer of graphene mounted on a silicon wafer. The researchers enhanced the sensing capabilities of the graphene layer by attaching a linker molecule to its surface. This linker serves as the anchor for an ion receptor and, ultimately, the lead ions.

Swinburne University of Technology and Sparc Technologies recently announced a collaboration, spearheading the evolution of smart coatings and composites through the Australian Research Council (ARC) research project. The partnership aims to revolutionize key industries, including aerospace, infrastructure, renewable energy, and more. 

Sparc Technologies' state-of-the-art facility enables the mass production of its graphene additive, Ecosparc. Denis Wright, general manager of Graphene Materials at Sparc, stating: “It is a very exciting opportunity to be contributing to this project and developing Ecosparc additives that will impart through their intrinsic properties, intelligence into coatings and composites.”

Researchers at  Monash University Malaysia and Tunku Abdul Rahman University of Management and Technology have studied how graphene and graphene derivatives could be used as materials to reduce the operating temperature of solar panels. They reviewed the limitations and potential of solar module cooling techniques based on graphene and found that high costs and graphene treatments are the main challenges to overcome.

In a recent in-depth review, the team explained that graphene has attracted the interest of the scientific community as a medium to enhance heat transfers in cooling systems. When used for PV cooling applications, graphene can be used in different ways. For example, as a selective absorber coating or embedding it into a working fluid as a nanofluid. Graphene nanoparticles can also be added to thermal interface materials (TIMs) or phase change materials (PCMs) used for solar module cooling.