From greenhouse gas to (super-)nanomaterial
Carbon dioxide is commonly known as a greenhouse gas and its effect on climate change. Less known is the fact that this gas can also serve as the base material for chemical reactions and useful material. One highly interesting application is the use of carbon dioxide for production of graphene.
Fossil energy carriers such as coal or mineral oil are burned for provision of energy for power, heat and mobility. On the downside, this increases the amount of carbon dioxide in the atmosphere, contributing to the ongoing climate change. To counteract this chain of causation has motivated scientists to look for alternative energy carriers, but also alternative forms of usage for carbon dioxide. One possibility could be the use of carbon dioxide as a cheap starting substance for synthesizing other materials. These could be reincorporated into the economic cycle – maybe even with a profit.
For inspiration, one mustn’t look further than just outside the window. Photosynthesis, the process of forming biomass from combining sunlight, water and carbon dioxide in the leaves of plants closes the natural carbon cycle. The metal-doped enzyme RuBisCo is essential to the process because it absorbs carbon dioxide from air, making it available for the further chemical processing in the plant. Scientists from the Institute for Technology in Karlsruhe, Germany (KIT) let themselves be inspired by this natural process. They have presented a process, in which carbon dioxide in conjunction with hydrogen is transformed directly into graphene on specially designed, catalytically active metal surfaces at temperatures up to 1000 degrees centrigrade.
Graphene is the two-dimensional mode of carbon, in which it possesses very useful electrical characteristics. This makes it interesting for application in new electronic applications. Graphene is, for all intents and purposes, a rising star on the horizon in technology. Its discovery and manageability in 2004 yielded a nobel prize in physics for the discoverers Andre Greim and Konstantin Novelov, and led to intensive research all over the world.
The method from several working groups at KIT was presented in the science journal ChemSusChem. It involves a metal catalyst with which graphene is produced from carbon dioxide and hydrogen. Prof. Mario Ruben, the leader of the study, explains: “If the metal surface has the correct ratio between copper and palladium, the transformation from carbon dioxide to graphene takes place in a simple, single-stage process.” Further experiments even led to production of multi-layer graphene, which could be interesting for use in batteries, electronic components or filtering materials. The next goal of the researchers is now to mold functioning electrical components. Carbon materials like graphene or magnetic molecules could also serve as building stones for quantum computers, which allow high-speed, energy-efficient calculations without relying on binary logic of today’s computers.
Source (German only): https://www.kit.edu/kit/pi_2019_090_graphen-aus-kohlendioxid.php