"More hydrogen can be stored at lower pressures and room temperature, making some of these materials good for practical use."Jose Mendoza-Cortes, Florida State University

A researcher at Florida State University (FSU) has designed new materials that could be used to store hydrogen fuel more efficiently in vehicles or other devices that use clean energy. Jose Mendoza-Cortes, an assistant professor in the College of Engineering at FSU, describes his proposed solution and designs for these new materials in a paper in the Journal of the American Chemical Society.

"There will be many proposals to solve energy issues, and this may be one option," Mendoza-Cortes said. "We wanted to find the most effective way to store hydrogen so that perhaps in the future, cars could use this to run longer distances and more efficiently."

Scientists had already discovered that they needed to pressurize hydrogen to compact it and make it usable as a fuel for cars. But Mendoza-Cortes wanted to take it one step further and make the process more efficient and economically viable. "We still want to pressurize it, but we want to do it more efficiently," he said. "Right now, it's extremely costly to do this."

Using complex mathematical equations and computer simulations, Mendoza-Cortes designed porous materials of transition metals – compounds involving cobalt, iron or nickel – that can efficiently bind hydrogen. These next-generation porous materials, known as covalent organic frameworks and made of Earth-abundant elements, could then be placed in the tank of a car that uses hydrogen for fuel.

Mendoza-Cortes designed 270 compounds through these simulations and then tested their ability at storing hydrogen. The idea is that since hydrogen will bind to the actual material, more hydrogen could be packed in and condensed into a tank, and because the hydrogen easily sticks to the material, the tank would never actually reach empty. What is more, less energy would be required to fill up a tank containing these materials.

"In other words, more hydrogen can be stored at lower pressures and room temperature, making some of these materials good for practical use," Mendoza-Cortes said.

As of 2016, three companies have produced hydrogen fuel cars – Toyota, Hyundai and Honda. Currently, hydrogen can be made into liquid at 1 bar – bar is the unit of measurement for atmospheric pressure – and 20K (-423.67°F), allowing hydrogen to be stored at a rate of 71 grams per liter. By contrast, at 700 bar and 298K (76.73°F), hydrogen can be stored at 37 grams per liter.

With Mendoza-Cortes' proposed new materials, hydrogen could be stored at less than 200 bar to fill up the same tank at room temperature, creating a far more efficient system. "You don't have to spend all that energy to get the same amount of storage," he said.

This story is adapted from material from Florida State University, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.