What is aerogel?
Aerogel is created by combining a polymer with a solvent to form a gel, and then removing the liquid from the gel and replacing it with gas (usually air). The high air content (99.98% air by volume) makes it one of the world's lightest solid material. Aerogels can be made from a variety of chemical compounds, and are a diverse class of materials with unique properties. They are known as excellent insulators, and usually have low density and low thermal conductivity.
Aerogels can be used in various applications, and although they have been around since the 1930s, their development is still progressing (for example, NASA's Glenn Research Center in Cleveland has invented several groundbreaking methods of creating new types of aerogels).
Common applications include enhancing the thermal performance of energy-saving materials and sustainable products for buildings, acting as a high performance additive to coatings, prevention of corrosion under insulation, uses in imaging devices, optics, and light guides, thermal breaks and condensation control, architectural lighting panels, outdoor and sports gear and clothing, and more.
Graphene aerogel, also known as aerographene, is considered to be the least dense solid in existence (graphene aerogels are light enough to be balanced on small plants!).
Graphene aerogels are quite elastic and can easily retain their original form after some compression. In addition, the low density of graphene aerogels makes them very absorbent (to the point where it can even absorb more than 850 times its own weight). This means that it could be useful for environmental clean-ups like oil spills, and the aerogels only need to be picked up later after absorbing the spilled material. Graphene aerogel may also have some applications in both the storage and the transfer of energy by enabling the creation of lighter, higher-energy-density batteries - and vigorous research is being done on the matter.
Graphene aerogel are somewhat similar to graphene foams. Graphene foams are usually made by CVD growth on a metal structure (which is later removed), and are so more conductive than graphene aerogels.
Graphene aerogels are already being sold commercially, for about about $300 per gram.
The latest Graphene Aerogel news:
Imagine Intelligent Materials and Swinburne University have announced a collaborative six-month project aiming to develop graphene-reinforced smart composites. The composite will be able to report on the condition of large structures, and will have major commercial potential in the transport sector, including automotive and aerospace.
The project is supported by a $20,000 Seed grant from the university under a program, targeting “interdisciplinary projects that are aligned with the Swinburne research institutes’ external partnership and collaboration objectives”. It will combine expertise from experts in sensors, electronics engineering and aerospace manufacturing at the university.
A collaboration work by Purdue, the Chinese Lanzhou University and Harbin Institute of Technology, and the U.S. Air Force Research Laboratory has yielded a lightweight, flame-resistant and super-elastic composite shown to combine high strength with electrical conductivity and thermal insulation, suggesting potential applications from buildings to aerospace.
The composite material is made of interconnected cells of graphene sandwiched between ceramic layers. The graphene scaffold, referred to as an aerogel, is chemically bonded with ceramic layers using a process called atomic layer deposition. The team explained that graphene would ordinarily degrade when exposed to high temperature, but the ceramic imparts high heat tolerance and flame-resistance, properties that might be useful as a heat shield for aircraft. The light weight, high-strength and shock-absorbing properties could make the composite a good substrate material for flexible electronic devices. Because it has high electrical conductivity and yet is an excellent thermal insulator, it might be used as a flame-retardant, thermally insulating coating, as well as sensors and devices that convert heat into electricity, said associate professor in the School of Industrial Engineering at Purdue University.
Guiness World Records has named a 3D printed graphene aerogel as "the least dense 3D printed structure". The 3D printed graphene aerogel, developed by a Kansas State University, University at Buffalo and Lanzhou University (China) team, weighs 0.5 milligrams per cubic centimeter. This achievement will be featured in the GUINNESS WORLD RECORDS 2018 Edition.
The way the researchers print the three-dimensional graphene is also regarded as revolutionary. The researchers use a modified inkjet printer that uses two nozzles. They 3D print droplets of a graphene oxide and water mixture in a freezer on a cold plate that is minus 20 degrees Celsius. This method creates a 3D ice structure of graphene and frozen water, which helps the graphene to maintain its shape.
Researchers at Zhejiang University in China have designed a graphene-based aerogel mimicking the structure of the "powdery alligator-flag" plant that could have potential for use in applications like flexible electronics.
The team drew inspiration from the stem structure of the powdery alligator-flag plant (Thalia dealbata), a strong, lean plant capable of withstanding harsh winds. The researchers used a bidirectional freezing technique that they previously developed to assemble a new type of biomimetic graphene aerogel that had an architecture like that of the plant's stem. When tested, the material supported 6,000 times its own weight and maintained its strength after intensive compression trials and was resilient. They also put the aerogel in a circuit with a LED and found it could potentially work as a component of a flexible device.
Researchers from China create graphene aerogel that converts sunlight into heat to produce water vapor at room temperature
Researchers at the Chinese Hubei University have designed a graphene aerogel film capable of producing water vapor at room temperature using only sunlight. The aerogel floats on the surface, where it heats up only a small part of the water column, ‘while the temperature of the bulk water is far below the boiling point’, the team explains.
This sunlight-harvesting graphene film could convert sea or wastewater into drinking water in places where fuel or access to electricity is limited. Desalinating seawater to make it drinkable usually means boiling it, and then collecting and condensing the steam. Heating water to its boiling point, however, requires quite a lot of energy, which is not always easy to come by. There are solar stills that desalinate water using only sunlight, but they’re slow and not always efficient enough to provide sufficient drinking water for a person’s daily needs.