Hydrogen, a future energy source, can now be stored more efficiently. It is expected that the efficiency and economic feasibility of hydrogen energy use will be increased as hydrogen can be stored at a high density.

Professor Oh Hyun-chul of the Department of Chemistry at UNIST (President Yong-Hoon Lee) reported a nanoporous magnesium borohydride structure (Mg(BH4)2) that can store hydrogen at high density even at normal atmospheric pressure.

Low hydrogen storage capacity, which is a problem in storing or transporting hydrogen, can be improved with high-density adsorption technology, making 'large-capacity hydrogen storage' possible.

Professor Oh Hyun-chul explained, “Unlike existing hydrogen storage methods, the developed material has the potential to safely and efficiently store large amounts of hydrogen.”

Hydrogen, which is attracting attention as a future fuel, has very weak intermolecular interactions, making it difficult to store it in large quantities for actual use. Large-scale storage was possible by significantly increasing the pressure to 700 atm or lowering the temperature to -253 degrees Celsius in the same volume, but the efficiency was not sufficient.

The research team has already created a nanoporous composite hydride, magnesium borohydride, using hydrogen-containing solid borohydride ((BH4)2) and the metal cation magnesium (Mg+).

It was confirmed that the hydrogen stored in the developed material is stored in a three-dimensionally aligned form of five hydrogen molecules. This means that hydrogen can be stored at a high density.

The reported material can store 144 g/L of hydrogen per pore volume. This is more than twice as high as the method of storing gaseous hydrogen molecules in a liquid state (density 70.8 g/L). Hydrogen molecules exist at a higher density than in a solid state (density 86 g/L).

Additionally, the research team used various analytical techniques (neutron scattering, cryogenic volume measurement, DFT calculations, etc.) to reveal the exact molecular locations and how a large amount of hydrogen can exist inside the pores.

Professor Oh Hyun-chul said, “This suggests the possibility of solving the problem of hydrogen storage, which is an important challenge in utilizing public transportation using hydrogen fuel,” and “It is an important development that can improve the storage density based on volume, which is difficult to achieve with current technology, and increase the efficiency and economic feasibility of hydrogen energy use.” He explained its significance.

The results of this study were published online on February 6 in Nature Chemistry, a world-renowned international academic journal in the field of chemistry. This study was conducted through the mid-career researcher support project supported by the National Research Foundation of Korea under the Ministry of Science and ICT.