Rice University - Page 4

The labs of Rice University chemist James Tour and Christopher Arnusch, a professor at Ben-Gurion University of the Negev in Israel, introduced a batch of graphene-enhanced composites that can be a step towards more robust packages.

By infusing laser-induced graphene with plastic, rubber, cement, wax or other materials, the lab made composites with a wide range of possible applications. These new composites could be used in wearable electronics, in heat therapy, in water treatment, in anti-icing and deicing work, in creating antimicrobial surfaces and even in making resistive random-access memory devices.

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.

Scientists at Rice University have enhanced their formerly invented LIG technique to produce what may become a new class of edible electronics. The Rice lab of Prof. James Tour is investigating ways to write graphene patterns onto food and other materials to embed conductive identification tags and sensors into the products themselves.

"This is not ink," Tour said. "This is taking the material itself and converting it into graphene". The process is an extension of the Tour lab's perception that anything with adequate carbon content can be turned into graphene. In recent years, the lab has developed and expanded upon its method to make graphene foam by using a commercial laser to transform the top layer of an inexpensive polymer film.

Researchers from Rice University have discovered that nitrogen-doped carbon nanotubes or modified graphene nanoribbons could potentially replace platinum, one of the most expensive facets in fuel cells, for performing fast oxygen reduction—a crucial reaction that transforms chemical energy into electricity.

The researchers used computer simulations to see how carbon nanomaterials can be improved for fuel-cell cathodes and discovered the atom-level mechanisms by which doped nanomaterials catalyze oxygen reduction reactions. The simulations also revealed why graphene nanoribbons and carbon nanotubes modified with nitrogen and/or boron are so sluggish and how they can be improved.

Researchers from Rice University have transformed wood into an electrical conductor by turning its surface into graphene. The team used its LIG technique to blacken a thin film pattern onto a block of pine.

Previous work with LIG included heating the surface of a sheet of polyimide, an inexpensive plastic, with a laser. Rather than a flat sheet of hexagonal carbon atoms, LIG is a foam of graphene sheets with one edge attached to the underlying surface and chemically active edges exposed to the air.

Scientists at Rice University and the University of Houston have developed a catalyst that can simplify the splitting of water into hydrogen and oxygen to produce clean energy. The electrolytic film is a three-layer structure of nickel, graphene and a compound of iron, manganese and phosphorus. The foamy nickel gives the film a large surface, the conductive graphene protects the nickel from degrading and the metal phosphide carries out the reaction.

The film was developed to overcome barriers that usually make a catalyst good for producing either oxygen or hydrogen, but not both simultaneously - as is often the case with regular metals. The team explained that normally, a hydrogen evolution reaction is done in acid and an oxygen evolution reaction is done in base. This work produced one material that is stable whether it's in an acidic or basic solution. In addition, the team used rather common materials in lieu of the usually-required platinum and other costly materials.