Monthly Archives: January 2020

Stretched to the Limit and Sparkling on Curved Surfaces

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Department of Energy’s Office of Science (BES) highlights our work with ORNL

Image courtesy of Oak Ridge National Laboratory

… Scientists use chemical vapor deposition to deposit WS2 films on substrates that have first been lithographically patterned with three-dimensional features such as trenches and tori (donut shapes).

The team has developed a model that explains that the accelerated crystal growth caused by the strain is because of an increase in the number of sites at which new particles are deposited during film growth (nucleation). When the height of the donut or trench is too high (above 40 nm), the strain becomes too high, and the films crack to release the strain.

– See more at energy.gov

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Rice lab turns trash into valuable graphene in a flash

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‘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