14 DAY TRIAL // A group of investigators announces the development of a theoretical model for the construction of a graphene nanoscale box, capable of acting as a hydrogen container several times more efficient than existing structures in this class. The nanobox can also be closed or opened at will, by applying an electric field, say researchers at the University of Maryland.
The team used computer modeling to investigate the potential behavior of graphene sheets in 3D structures. Graphene is a 2D pure carbon compound that features a hexagonal structure, and very useful physical and chemical properties. First synthesized just a decade ago, graphene is now one of the most studied materials in the world, and believed to be the basis for future generations of electronics.
The computer model the team developed was meant to test how 1-atom-thick graphene sheets would react to electrical fields. Scientists were able to demonstrate that applying such fields in the correct pattern leads graphene to self-assemble into 3D cube-like boxes, which can be filled with other molecules, ranging from drugs to hydrogen for power storage.
UM investigators say that this approach to folding up the carbon compound has been designated as hydrogenation-assisted graphene origami (HAGO). The only pre-requisite for assembling the box is to cut the carbon sheets in specific patterns, in essence creating hinges on which square of graphene can turn to create the cube. The entire object is then made functional through the addition of hydrogen.
The team says that graphene assembles into box-like structures on its own, without the need for external influences. The electric fields are required in order to open up the nanobox, and release its contents. “First, a suitably functionalized and patterned graphene can spontaneously fold into a 3-D nanostructure […] No external electric field is needed,” researcher Teng Li explains.
“Second, an electric field can cause the polarization of the graphene, effectively reducing the graphene inter-layer adhesion, which causes the folded nanostructure to unfold,” adds the expert, who is an associate professor of mechanical engineer with UM. “Upon turning off the electric field, the graphene folds up into a box spontaneously again. Such a process can be repeated many times,” he adds.
The new study, entitled Hydrogenation-Assisted Graphene Origami and Its Application in Programmable Molecular Mass Uptake, Storage, and Release, was published in the latest issue of the esteemed scientific journal ACS Nano, IEEE Spectrum reports.
The team says that graphene nanoboxes have a hydrogen-storage capacity of 9.7 percent by weight. This level is significantly higher than the thresholds set for the alternative energy industry by the US Department of Energy. The DOE called for a storage capacity of 5.5 percent to be achieved by 2017, followed by a 7.5 percent capacity by 2020.
“Much effort has been dedicated in this research to demonstrate the promising feasibility of the HAGO process, including its robustness to possible manufacturing defects and stability at room temperature. We will actively pursue collaborations with experimentalists to actually demonstrate,” Li concludes.