Flash Graphene can Come from Our Trashes.

James Tour, a chemist from Rice University has introduced a new process in the lab. This cheap and quick process is able to turn any carbon source into graphene flakes in a massive amount. Tons of coal, plastic and food wastes can be transformed into flash graphene; Tour says. The current methods for producing graphene are far more costly than this new technique. It will surely save a lot in spending graphene production with this new process as it will take a fraction of the previous cost. 

Tour says, "This is a big deal. The world throws out 30% to 40% of all food, because it goes bad, and plastic waste is of worldwide concern. We've already proven that any solid carbon-based matter, including mixed plastic waste and rubber tires, can be turned into graphene."

The current process of making graphene is available in Nature. According to the report, when carbon materials are heated to 3,000 Kelvin or 5,000 degrees Fahrenheit for 10 milliseconds, then we can get flash graphene. The source material can be any kind of carbon material. The list of carbon contents is big including food waste, coal, plastic waste, wood clippings, biochar, etc. Tour says, "With the present commercial price of graphene being $67,000 to $200,000 per ton, the prospects for this process look superb." 

In a report, we come to know that cement production is responsible for emitting 8% carbon dioxide every year that humans make. Tour says that this carbon emission can be reduced to one third by using even a tiny amount like 0.1% of flash graphene in cement. 

He adds, "By strengthening concrete with graphene, we could use less concrete for building, and it would cost less to manufacture and less to transport. Essentially, we're trapping greenhouse gases like carbon dioxide and methane that waste food would have emitted in landfills. We are converting those carbons into graphene and adding that graphene to concrete, thereby lowering the amount of carbon dioxide generated in concrete manufacture. It's a win-win environmental scenario using graphene."

The study’s co-corresponding author is Rouzbeh Shahsavari. He is an adjunct assistant professor of materials science and nanoengineering and civil and environmental engineering the Rice University. He is also the president of C-Crete Technologies. He says, "Turning trash to treasure is key to the circular economy. Here, graphene acts both as a 2D template and a reinforcing agent that controls cement hydration and subsequent strength development."

Tour said, "In the past graphene has been too expensive to use in these applications. The flash process will greatly lessen the price while it helps us better manage waste."

"With our method, that carbon becomes fixed. It will not enter the air again," he adds. 

Carbon Hub initiative is a recent announcement by the Rice University. The initiative aims at creating zero-emissions in the future exactly matches the initiatives. The process repurposes hydrocarbons from oil and gas to generate hydrogen gas and solid carbon with zero emission of carbon dioxide. Tour’s process can transfer solid carbons into graphene. He says the graphene is very useful for concrete, buildings, clothing, cars, and more.  

The earlier technique was costly and effort taking but produced less graphene. But, Tour’s lab developed a special Flash Joule heating for bulk graphene. A Rice graduate, Duy Luong improves the exfoliation technique. He is also a lead author of the study. 

Being cost-effective, the process produces "turbostratic" graphene that is even better the earlier versions. Moreover, we can separate the misaligned layers easily. Tour says, "A-B stacked graphene from other processes, like exfoliation of graphite, is very hard to pull apart. The layers adhere strongly together.”

As the layers adhere to levels that are lower in turbostratic graphene, it is easier to work with them. He says, "That's important because now we can get each of these single-atomic layers to interact with a host composite."  

While completing their research in the lab, the team noticed pristine single-layer sheets of graphene transformed from used coffee grounds. 

Graphene is important for metals, concrete, plastic, plywood, and building materials. So, the researchers believe that its market is huge. They are already working on graphene-enhanced concrete and plastic.

The team uses a custom-designed reactor to complete the flash process. After hitting the metal, this process releases the noncarbon elements by converting them into gas. Tour says, "When this process is industrialized, elements like oxygen and nitrogen that exit the flash reactor can all be trapped as small molecules because they have value." 

He confirms that this process generates light heat and all the energy focuses on the target. He says, "You can put your finger right on the container a few seconds afterward. And keep in mind this is almost three times hotter than the chemical vapor deposition furnaces we formerly used to make graphene, but in the flash process the heat is concentrated in the carbon material and none in a surrounding reactor.”

"All the excess energy comes out as light, in a very bright flash, and because there aren't any solvents, it's a super clean process," he adds.

When Luong started the reactor with a small-scale limit with a sample of carbon black, he unexpectedly found high-quality graphene. Although he was trying to find out new phases of material, he ended up finding graphene. He says, "This started when I took a look at a Science paper talking about flash Joule heating to make phase-changing nanoparticles of metals,"

Ksenia Bets is a co-author of the study and confirmed temperature plays a vital role in the rapid formation of the materials. She says, "We essentially speed up the slow geological process by which carbon evolves into its ground state, graphite. Greatly accelerated by a heat spike, it is also stopped at the right instant, at the graphene stage.”

Bets also says, "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."

Recently, the Department of Energy has funded a project to convert U.S-sourced coal. If this project runs successfully, within two years, Tour is hoping to produce a kilogram (2.2 pounds) graphene per day. He says, "This could provide an outlet for coal in large scale by converting it inexpensively into a much-higher-value building material."