Rice University and Iran University of Science and Technology researchers have found a unique ceramic material that could act as a sensor for structures.
The ceramic becomes more electrically conductive under elastic strain and less conductive under plastic strain, and could lead to a new generation of sensors embedded into structures like buildings, bridges and aircraft able to monitor their own health.
Rice University scientists have developed a graphene-based epoxy for electronic applications. Epoxy combined with graphene foam invented in the Rice lab of Prof. James Tour) is reportedly substantially tougher than pure epoxy and far more conductive than other epoxy composites, while retaining the material's low density. It could improve upon epoxies in current use that weaken the material's structure with the addition of conductive fillers.
By itself, epoxy is an insulator, and is commonly used in coatings, adhesives, electronics, industrial tooling and structural composites. Metal or carbon fillers are often added for applications where conductivity is desired, like electromagnetic shielding. The trade-off, however, is that more filler brings better conductivity at the cost of weight and compressive strength, and the composite becomes harder to process. The Rice solution replaces metal or carbon powders with a 3D foam made of nanoscale sheets of graphene.
Rice University scientists have developed a simple way to create conductive, 3D objects made of graphene foam. The resulting objects may offer new possibilities for energy storage and flexible electronic sensor applications, according to Rice chemist Prof. James Tour.
The technique is an extension of groundbreaking work by the Tour lab that produced the first laser-induced graphene (LIG) in 2014 by heating inexpensive polyimide plastic sheets with a laser. The laser burns halfway through the plastic and turns the top into graphene that remains attached to the bottom half. LIG can be made in macroscale patterns at room temperature.
Researchers at Rice University have demonstrated the mechano-chemical assembly of functionalized graphene layers into 3D graphitic solids (“graphite pellets”) via room temperature and low energy consuming processing. The pellet material is reportedly stronger and lighter than commercial graphite electrodes and could be promising for electrical storage applications with high energy and power densities.
The environmentally friendly, scalable process can be done in minutes by hand by grinding chemically modified graphene into a powder and using a hand-powered press to squeeze the powder into a solid pellet. The team demonstrated how to make a battery-sized pellet, but the graphene powders with chemical functionalities attached to it can be pressed into any form. They said the material could be suitable for structural, catalytic, electrochemical and electronic applications.
Rice University scientists, led by Prof. James Tour, along with teams from the University of Texas at San Antonio and the Chinese Academy of Sciences, Beijing, China have detected a deception in graphene catalysts that, until now, gone unnoticed. Graphene has been widely tested as a replacement for expensive platinum in applications like fuel cells, where the material catalyzes the oxygen reduction reaction (ORR) essential to turn chemical energy into electrical energy.
Since graphene isn't naturally metallic, researchers have been baffled by its catalytic activity when used as a cathode. The Rice team has now discovered that trace quantities of manganese contamination from graphite precursors or reactants hide in the graphene lattice. Under the right conditions, those metal bits activate the ORR. Tour said they also provide insight into how ultrathin catalysts like graphene can be improved.