Scientists at the Berkeley National Laboratory have developed a mix of metal nanocrystals wrapped in graphene that may be a huge step in storing hydrogen and may lead to the creation of a new type of fuel cell.
Graphene is a thin sheet of carbon that is approximately 200 times stronger than steel and is an excellent electrical conductor. The team of scientists studied how the ultrathin sheet of carbon can be used as both selective shielding, as well as a performance increasing factor in terms of hydrogen storage.
The study put the laboratory’s capabilities in terms of creating and coating microscopic magnesium crystals to the test. Equally challenging proved the task of using x-rays in order to study their chemical composition, and developing computer simulations.
The scientists have gained extensive knowledge with regard to how other coatings could also improve the performance, as well as the stability of other materials that may revolutionize the current hydrogen storage technology.
The study is part of a larger project called Hydrogen Materials – Advanced Research Consortium, organized by the U.S. Department of Energy’s Fuel Cell Technologies Office.
The technology could prove to be useful in terms of hydrogen storage due to the fact that reduced graphene oxide has nanoscale holes that allow only small hydrogen molecules to pass through.
In theory, the material used to coat magnesium crystals(which are used to store hydrogen) should have prevented them from reacting with oxygen, water vapor and carbon dioxide that can be found in the atmosphere. The coating practically serves as a shield against oxidation.
Unfortunately, the magnesium crystals still developed a layer of oxidation, but this did not have a negative impact on the material’s performance. Quite to the contrary actually. It seems that the oxide layer has increased the interaction between the graphene oxide and the magnesium. This has come as a surprise, due to the fact that, until now, it was thought that oxidation lowers the efficiency of materials that are used to store hydrogen.
The director of the Molecular Foundry’s Theory Facility participated in the study and stated the fact that the current hydrogen-powered vehicles come with heavy tanks that limit their driving efficiency and range.
This problem could be eliminated by using other materials such as magnesium nanocrystals in order to store hydrogen. Furthermore, the use of nanocrystals would improve the fuel capacity of hydrogen-powered vehicles, as they can absorb much more gas than the amount that is normally compressed in a fuel tank, at the same pressure.
The scientists have also determined that the oxidation layer does not grow over time, which means that the crystals do not degrade.