Researchers Produce Graphene Using Coal
A team of researchers at Virginia Tech have reportedly been looking into how graphene can be produced using coal to improve existing materials and technologies without adding too much extra mass.
According to a release from the university, the team believes that this new production method could prove to be more cost-effective and environmentally friendly, while also creating new ways to incorporate graphene into everyday products.
The team is led by Roop Mahajan, Lewis A. Hester Professor in Mechanical Engineering at Virginia Tech with a joint appointment in Materials Science and Engineering.
About the Research
The team states that due to its blend of properties, graphene could be used for many purposes, including cars and planes, clothing, antimicrobial agents, water filtration systems and more. Additionally, the report states that graphene could open the door for “wearable electronics.”
Because graphene consists mainly of carbon, researchers stated that they had to use a material naturally high in carbon. Graphite, the main component of pencil lead, is reportedly the typical choice due to its composition being almost total carbon.
Because graphene is a one-atom-thick sheet of material, creating it reportedly demands a considerable amount of processing. The most common technique is reportedly an altered version of an approach called the Hummer’s Method, using sulfuric acid, potassium permanganate, sodium nitrate and hydrogen peroxide at different stages. Three of those four chemicals are reportedly considered hazardous.
However, Mahajan’s team states that they have come up with a better method for sourcing graphene. According to the team, they have begun gathering graphene from coal instead of graphite, cutting the number of harsh chemicals to only one: nitric acid.
With fewer hazardous chemicals and less disposal to manage, this approach is expected to reduce the environmental impact and the risk to researchers.
Replacing graphite as the main source for future materials could come with benefits. Most graphite is reportedly sourced from China, making the supply chain unpredictable.
On top of that, graphite is reportedly a major ingredient in batteries, and the increase in global demand for batteries has taken a large chunk out of that supply.
Researchers state that coal only has 60% to 80% of carbon in it compared to an almost 100% composition in graphite. Because of this, the team believes that a shift to coal could open opportunities for a coal economy quickly diminished across the world, in large part due to its contribution to global warming when burning coal.
In addition to the environmental benefits, the process is reportedly less expensive than prior methods, creating a lower-cost supply that may spark new innovations in the market and aid in commercialization.
“Lowering the production cost of graphene is crucial to fully harness its exceptional properties and accelerate its broad adoption across diverse applications, potentially catalyzing the development of new markets and industries,” Mahajan said.
Creating the Graphene
In Mahajan’s new development, generating graphene begins with grinding down raw chunks of coal to create a coarse powder. The powder is then reportedly placed into a large cylinder with white marbles of different sizes, then rolled.
The marbles grind and crush the dust, reducing its size. Then, the milled powder is chemically stripped of impurities like metal sulfites and ash.
The ground and purified coal is then reportedly put in a bath of nitric acid, converting the coal into graphene oxide. The acid is drained, and the unreacted carbon is removed, leaving graphene oxide powder that can then be further converted to graphene by heat treatment.
This is reportedly the substance that has been mixed with adhesives, silicon, glass and metal to create new composite materials for several applications.
The new research has reportedly left a steady stream of publications, including one in the journal Carbon.
This paper explains the team's process and demonstrates the advantages of coal-derived graphene in the development of highly sensitive sensors to divide and detect single-stranded DNA aptamers.
The sensors are reportedly often used in diagnostics, therapeutics, food safety and other industries due to their ability to link to specific target molecules with high affinity and specificity.
Now, to expand the team’s findings, Mahajan, who is also the director of strategic research and innovation for Virginia Tech's Centre for Advanced Research and Education in India, has begun pushing innovation there as well. According to the release, this team of scientists, headquartered in Chennai, India, has been vital to growing this graphene enterprise.
Research produced from this team reportedly appeared in a recent article in ACS Applied Nanomaterials focusing on graphene oxide’s role as a nanofiller in enhancing the mechanical performance of glass fiber-reinforced polymers.
The team stated that they are now looking into other potential applications, including:
While creating new technologies provides a new scientific environment, Mahajan states that he is focused on more than just innovation. Reducing environmental hazards and boosting production on the new material reportedly has larger implications.
The new graphene, Mahajan states, could improve the quality of life for everyone, creating smarter energy use, more reliable materials and options for health care.
“This wide spectrum of applications exemplifies the remarkable potential of coal-derived graphene technologies in reshaping industries and improving lives on a global scale,” Mahajan said.
In January, researchers from Rice University and the University of Calgary, Canada, transformed a crude oil byproduct, asphaltene, into graphene for thermal, anti-corrosion and 3D printing applications.
Muhammad Rahman, an assistant research professor of materials science and nanoengineering, was a lead corresponding author of the paper in the journal Science Advances, alongside Rice chemist James Tour, materials scientist Pulickel Ajayan and Md Golam Kibria, an assistant professor of chemical and petroleum engineering at the University of Calgary, Canada.
Using the university's flash Joule heating process, Rahman was converting asphaltenes into turbostratic, or loosely aligned, graphene to mix with composites. Rice reported that this process uses up material otherwise burned for reuse as fuel or discarded into tailing ponds and landfills.
Additionally, the world reportedly has a reserve of more than 1 trillion barrels of asphaltene. Using some of this reserve, Rice said, as a feedstock for graphene would be beneficial for the environment.
According to the release, since asphaltenes are already 70% to 80% carbon, researchers combined it with about 20% of carbon black to add conductivity. They then flashed it with a jolt of electricity, reportedly turning it into graphene in less than a second.
Any other elements in the feedstock, such as hydrogen, nitrogen, oxygen and sulfur, are vented away as gases.
The research was funded by the Alberta Innovates for Carbon Fiber Grand Challenge programs, the Air Force Office of Scientific Research, the U.S. Army Corps of Engineers and the National Science Foundation.
Additionally, in September, the ChemQuest Technology Institute entered a three-year, collaborative innovation agreement to support the growth and validation of Universal Matter’s graphene technology.
Based on sustainable feedstocks, ChemQuest intended to explore the benefits of the graphene technology in applications for paints and coatings. The company also planned to identify the most valuable markets and opportunities for growth.
According to a press release issued by ChemQuest, Universal Matter produces its graphene using rapid, flash-fired bursts of electrical energy. The process enables the bonding of carbon into few layers of turbostratic graphene, as opposed to AB-stacked (Bernal) graphene, resulting in exceptional performance benefits in the target applications.
The flash process was modularized into compact manufacturing units and can be scaled by adding more modules of identical configuration. Many different carbon-based feedstocks can be transformed into high-purity turbostratic graphene using this flash process, the company added.