Scientists discover white graphene architecture with hydrogen storage potential

Boron nitride-based structure could be used for safe hydrogen storage to fuel vehicles

Scientists at Rice University in Texas have discovered a new type of white graphene architecture that contains an "unprecedented" capability for storing hydrogen.

The researchers claim to have developed a new form of optical architecture that can store hydrogen within rare nanomaterials, potentially enabling hydrogen to be used to safely fuel vehicles and other devices.

The researchers described the concept as "a Lilliputian skyscraper with floors of boron nitride sitting one atop another and held precisely 5.2 'angstroms' apart by boron nitride pillars". The findings have been published in the academic journal Small, published here.

Lead researcher Rouzbeh Shahsavari, who works as an assistant professor of civil and environmental engineering at the University, said that it can be challenging to store hydrogen safely. But this discovery could change that.

"The motivation is to create an efficient material that can take up and hold a lot of hydrogen - both by volume and weight - and that can quickly and easily release that hydrogen when it's needed," said Shahsavari.

Hydrogen, which is one of the lightest substances on Earth, can be used to generate electricity. However, it is challenging to use when things like portability, storage and safety are taken into account - as a gas at normal temperatures, it is highly flamable.

But after spending months producing calculations on two supercomputers, Shahsavari and Rice graduate Shuo Zhao believe that they have found a way to keep hydrogen in boron nitride.

This material could potentially eradicate the aforementioned safety and storage challenges. Previous research from Shahsavari's team suggests that it could help the US Department of Energy hit storage targets for fuel technology.

"The choice of material is important. Boron nitride has been shown to be better in terms of hydrogen absorption than pure graphene, carbon nanotubes or hybrids of graphene and boron nitride," he said.

"But the spacing and arrangement of hBN [hexagonal boron nitride] sheets and pillars is also critical. So we decided to perform an exhaustive search of all the possible geometries of hBN to see which worked best.

"We also expanded the calculations to include various temperatures, pressures and dopants, trace elements that can be added to the boron nitride to enhance its hydrogen storage capacity."

Zhao and Shahsavari applied common principles of physics to generate a range of ab initio calculations, which enabled them to come up with more precise results.

"We conducted nearly 4,000 ab initio calculations to try and find that sweet spot where the material and geometry go hand in hand and really work together to optimise hydrogen storage," said Shahsavari.

He explained that the diversity of boron nitride is one of the reasons it is so appealing as a storage element.

"Furthermore, the high thermal conductivity and flexibility of boron nitride may provide additional opportunities to control the adsorption and release kinetics on-demand.

"For example, it may be possible to control release kinetics by applying an external voltage, heat or an electric field."