Scientists and researchers at the University of Hong Kong and Northwestern University have developed a supramolecular material that can compress hydrogen for storage without increasing its weight.

The study, ‘Balancing volumetric and gravimetric capacity for hydrogen in supramolecular crystals,’ was published in Nature Chemistry.

The study reports a “controlled catenation strategy” used in hydrogen-bonded organic frameworks (RP-H100 and RP-H101). This approach relies on multiple hydrogen bonds to direct the catenation process precisely through point-contact interactions. As a result, these frameworks achieve high surface areas in terms of volume and weight, exhibit strong durability, and have optimal pore sizes (around 1.2–1.9 nm) that are well-suited for hydrogen storage.

Hydrogen has been widely regarded as the future fuel because of its zero-emission and high gravimetric energy density compared with gasoline. However, its low volumetric density requires 700-bar compressed tanks for its current storage and transportation, leading to a situation that is not only costly but also has safety concerns.

Research across the world has been conducted to address the issue. “The United States Department of Energy (US DOE) has established the following metrics to develop hydrogen-storage systems: a gravimetric storage capacity of 6.5 wt% and a volumetric storage capacity of 50 g,” the report read.

The material consists of organic molecules arranged in a honeycomb-shaped crystal structure with pores optimized for hydrogen molecules—the molecules bond with the crystals, enabling efficient storage.

Testing of the material shows that it can store 53.7g of hydrogen per liter of material, which makes up 9.3% of the system’s overall weight.

The report explains that a hydrogen-bond-directed catenation strategy was developed to create highly porous supramolecular crystals. This approach forms a seven-fold catenated superstructure through point-contact interactions driven by hydrogen bonds. This design gives the crystals high volumetric and gravimetric surface areas, increased structural strength, and customized pore sizes (around 1.2–1.9 nm), making them ideal for hydrogen storage.

The research report indicated the potential of supramolecular crystals as promising candidates for onboard hydrogen storage.

In May, researchers at Tohoku University in Japan developed a data-driven model that can predict barriers related to dehydrogenation. This reaction involves the release of hydrogen in magnesium hydride, a promising material for solid-state hydrogen storage.

Solid-state hydrogen binds the gas to a metal hydride using moderate heat and pressure. The material can then be safely stored at an average temperature and pressure without any hydrogen escaping.

In June 2024, Stanford University researchers made significant advancements in a new technology that employs liquid organic hydrogen carriers (LOHCs) as a “liquid battery” for storing renewable energy from sources like wind and solar. Led by chemistry professor Robert Waymouth, the team developed a catalytic system capable of efficiently transforming electricity into the liquid fuel isopropanol (rubbing alcohol) without producing gaseous hydrogen as a byproduct.