Category Archives: Collaboration

Rice scientists pull off quantum coup

Posted on by

Study validates method for guided discovery of 3D flat-band materials

Rice University scientists have discovered a first-of-its-kind material, a 3D crystalline metal in which quantum correlations and the geometry of the crystal structure combine to frustrate the movement of electrons and lock them in place.

The find is detailed in a study published in Nature Physics. The paper also describes the theoretical design principle and experimental methodology that guided the research team to the material. One part copper, two parts vanadium and four parts sulfur, the alloy features a 3D pyrochlore lattice consisting of corner-sharing tetrahedra.

Yakobson Research Group performed first-principle calculations that quantified the flat-band effects produced by geometric frustration.

Quantum materials are a likely place to look, especially if they host strong electron interactions that give rise to quantum entanglement. Entanglement leads to strange electronic behaviors, including frustrating the movement of electrons to the point where they become locked in place.

–  See more at Rice News

Related

‘Defective’ carbon simplifies hydrogen peroxide production

Posted on by

Plasma processing modifies carbon black powder to catalyze valuable chemical

Rice University researchers have created a “defective” catalyst that simplifies the generation of hydrogen peroxide from oxygen.

Rice scientists treated metal-free carbon black, the inexpensive, powdered product of petroleum production, with oxygen plasma. The process introduces defects and oxygen-containing groups into the structure of the carbon particles, exposing more surface area for interactions.

When used as a catalyst, the defective particles known as CB-Plasma reduce oxygen to hydrogen peroxide with 100% Faradaic efficiency, a measure of charge transfer in electrochemical reactions. The process shows promise to replace the complex anthraquinone-based production method that requires expensive catalysts and generates toxic organic byproducts and large amounts of wastewater, according to the researchers.

The research by Rice chemist James Tour and materials theorist Boris Yakobson appears in the American Chemical Society journal ACS Catalysis.

– See more at Rice News

Rice lab turns trash into valuable graphene in a flash

Posted on by

‘Green’ process promises pristine graphene in bulk using waste food, plastic and other materials

A new process introduced by the Rice University lab of chemist James Tour can turn bulk quantities of just about any carbon source into valuable graphene flakes. The process is quick and cheap; Tour said the “flash graphene” technique can convert a ton of coal, food waste or plastic into graphene for a fraction of the cost used by other bulk graphene-producing methods.

As reported in Nature, flash graphene is made in 10 milliseconds by heating carbon-containing materials to 3,000 Kelvin (about 5,000 degrees Fahrenheit). The source material can be nearly anything with carbon content. Food waste, plastic waste, petroleum coke, coal, wood clippings and biochar are prime candidates, Tour said. “With the present commercial price of graphene being $67,000 to $200,000 per ton, the prospects for this process look superb,” he said.

Atom-level simulations by Rice researcher and co-author Ksenia Bets confirmed that temperature is key to the material’s rapid formation.“It is amazing how state-of-the-art computer simulations, notoriously slow for observing such kinetics, reveal the details of high temperature-modulated atomic movements and transformation,” Bets said.

– See more at Rice News