Results of modeling studies indicate that attaching titanium atoms (blue) to the ends of an ethylene molecule (yellow-green) will result in a capsule-shaped complex that absorbs 10 hydrogen molecules (red). The results open a new avenue in the pursuit of materials that will enable efficient solid-state storage of hydrogen.

Image courtesy of NIST

New research by the National Institute of Standards and Technology (NIST, shows that ethylene might be a good fit for storing hydrogen, which is being touted by many as the transportation fuel of the future. Findings reported by scientists from NIST and Turkey’s Bilkent University ( predicts that “ethylene, a well-known inexpensive molecule, can be an important basis in developing frameworks for efficient and safe hydrogen-storage media.”

The research team’s calculations show that attaching titanium atoms at opposite ends of an ethylene molecule (four hydrogen atoms bound to a pair of carbon atoms) will result in a very attractive “two for” deal, according to a report by NIST. The addition of the two metal atoms results in a net gain of up to 10 hydrogen molecules that can absorb onto the ethylene-titanium complex, for a total of 20 hydrogen atoms. As important, NIST says the engineered material will release the hydrogen with only a modest amount of heating.

The absorbed hydrogen molecules account for about 14 percent of the weight of the titanium-ethylene complex — approximately double the Department of Energy’s ( minimum target of 6.5 percent for economically practical storage of hydrogen in a solid-state material. While NIST acknowledges that significant challenges remain to be overcome before this process is ready for real-world applications, it believes solid-state storage is preferred to storing hydrogen as a liquid or compressed gas, both of which require large-volume tanks. The research team anticipates that ethylene-based complexes, made with titanium or other so-called transition metals, will prove easier to synthesize and, then, to evaluate for their potential for high-capacity hydrogen storage.