The first graphene production approach that uses carbon monoxide as the carbon source has been proposed by researchers. It's a straightforward and quick approach to make high-quality graphene for use in electrical circuits, gas sensors, optics, and other applications. Researchers from Skolkovo Institute of Science and Technology (Skoltech), Moscow Institute of Physics and Technology (MIPT), the RAS Institute of Solid State Physics, Aalto University, and other institutions collaborated on the work, which was published in the respected journal Advanced Science.
Chemical vapor deposition (CVD) is the industry standard for producing graphene, a one-atom-thick sheet of carbon atoms arranged in a honeycomb pattern with unrivaled features valuable for electronics and other uses. Carbon atoms break free from gas molecules and settle as a monolayer on a substrate in a vacuum chamber during CVD. The gases employed have always been hydrocarbons: methane, propane, acetylene, spirits, and so on.
“The idea to synthesize graphene from carbon monoxide came a long time ago, since that gas is one of the most convenient carbon sources for the growth of single-walled carbon nanotubes. We have had working experience with carbon monoxide for almost 20 years. However, our first experiments with graphene were unsuccessful, and it took us a long time to understand how to control the nucleation and growth of graphene. The beauty of carbon monoxide is in its exclusively catalytic decomposition, which allowed us to implement self-limiting synthesis of large crystals of single-layer graphene even at ambient pressure,” the study’s principal investigator, Skoltech Professor Albert Nasibulin states.
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| Graphene is a single layer of carbon atoms arranged in a two-dimensional honeycomb lattice nanostructure. |
“This project is one of the brilliant examples of how fundamental studies benefit applied technologies. The optimized conditions leading to the formation of large graphene crystals became feasible owing to an understanding of the deep kinetic mechanism for graphene formation and growth verified by both theory and experiment,” says Dmitry Krasnikov, a co-author of the article.
The novel strategy takes advantage of the so-called self-limiting principle. When carbon monoxide molecules approach close to the copper substrate at high temperatures, they tend to split up into carbon and oxygen atoms. This propensity fades when the first layer of crystalline carbon is produced and isolates the gas from the substrate, thus the process naturally promotes the production of a monolayer. Methane-based CVD can potentially be self-limiting, although only to a limited extent.
“The system we used has a number of advantages: The resulting graphene is purer, grows faster, and forms better crystals. Moreover, this tweak prevents accidents with hydrogen and other explosive gases by eliminating them from the process altogether,” adds Skoltech intern Artem Grebenko, the study's author.
There is no need for a vacuum since the procedure eliminates the possibility of combustion. The device operates at ordinary pressure, making it far easier to use than traditional CVD equipment. As a result of the simpler design, synthesis is quicker. Grebenko claims that it takes only 30 minutes to extract graphene from a bare piece of copper.
Because suction is no longer required, the equipment not only performs better but also costs less.“Once you drop the high-end hardware for generating ultrahigh vacuum, you can actually assemble our ‘garage solution’ for no more than $1,000,” the researcher notes.