Hydrogen may have immense potential as a future fuel for cars and in various industries. Well, scientists working on making this chemical element a promising alternative can possibly benefit from the following discovery. Investigators from the Rice University have apparently found a class of power-storing materials known as metallacarborane that can easily surpass the benchmarks set by the United States Department of Energy (DOE) Hydrogen Program for 2015.
In order to hold together a load of hydrogen molecules, researchers lightly tapped the power of transition metals scandium and titanium. Metallacarboranes can develop a matrix which could probably hold up to 8.8 percent of its weight in hydrogen atoms. This percentage seems to be very low for meeting and exceeding DOE guidelines laid down a year ago for cars running on hydrogen fuel. Molecules such as boron, carbon and metal atoms are known to combine very easily in a cage-like structure. Experts believe that a single metal atom can bind multiple hydrogen molecules, but metals tend to aggregate. They may clump into a blob and therefore be of no use.
Boris Yakobson Rice theoretical physicist, enlightened, “Kubas is a special interaction that you often see mentioned in hydrogen research, because it gives exactly the right binding strength. If you remember basic chemistry, you know that covalent bonds are very strong. You can bind hydrogen, but you cannot take it out. And on the other extreme is weak physisorption. The molecules don’t form chemical bonds. They’re just exhibiting a weak attraction through the van der Waals force. Kubas interaction is in the middle and gives the right kind of binding so hydrogen can be stored and, if you change conditions — heat it up a little or reduce pressure — it can be taken out. You want the framework to be like a fuel tank.”
Boron clusters that possibly grip the titanium and scandium further binding hydrogen were measured. Metals appear to fit like gem in a setting and don’t accumulate. Experts claim that carbon links with the clusters to form a matrix known as metal organic framework (MOF), which can act like a sponge for hydrogen. Having conducted various transition metals, it was ascertained that scandium and titanium have the highest rate of adsorption. It was elucidated that adsorption means the adhesion of transient molecules like hydrogen to a surface. Both titanium and scandium display an affinity for ‘Kubas’ interaction. In this interaction a trading of electrons is initiated which may bind atoms to one another in certain circumstances.
Reversible storage of hydrogen is supposedly acquired in Kubas, but only during ambient conditions that range from well above or well below room temperature. This process may make metallacarborane materials highly eligible for daily usage. Also physisorption of hydrogen can probably occur at a much lower percentage by the carbon matrix. Prior investigations have seemingly highlighted ways to make carborane-based MOFs. So, three-dimensional frameworks of material still appear accessible to gas.
The research is published in the online Journal of the American Chemical Society.