Hydrogen fuel cell. Image: scientific photo – Shutterstock

A survey synthesizes MOFs (organometallic materials) capable of facilitating the optimization of both the dimensions and the weight of the tank of “green” vehicles.

Using ultra-porous materials, researchers at Northwestern University are improve hydrogen storage and methane for fuel cell vehicles.

Northwestern University research team synthesized new materials with very high surface porosity through which hydrogen and methane can be stored for fuel cell vehicles. These organometallic materials (MOF) indeed have the particularity of being able to store much more hydrogen and methane than others, under much safer conditions and at much lower costs.

Thinking of clean energy vehicles, “we have developed a more efficient and safer on-board storage method, using chemical principles to design materials whose atomic disposition we can control, resulting in high porosity“Said Omar K. Farha, head of the investigation team.

These materials, called adsorbents, are porous solids that bind liquid or gaseous molecules to their surface. Thanks to these nanoscopic pores, 1 gram of this material has an area that would cover 1.3 football fields. In addition to fuel cell vehicles, adsorbent materials could be a breakthrough for the general gas storage industry, where many applications require the use of compressed gases such as oxygen, hydrogen and methane.

Specifically, ultra-pure MOFs, called NU-1501, are built with organic molecules and metal ions that self-assemble to form highly crystalline, porous multidimensional structures. To represent the structure of an MOF, imagine a set of toy toys, in which metal ions are the nodes and organic molecules are the bars that hold the nodes together.

Fuel cell vehicles currently require high pressure compression to operate. To get an idea, the pressure in a hydrogen tank is 300 times greater than the pressure in a car’s tires. However, due to the low density of hydrogen, it is very expensive to achieve these pressure levels, as well as dangerous due to the high flammability of hydrogen and methane.

For this reason, it is necessary to optimize both the size and the weight of the fuel tank. Highly porous materials are able to precisely balance the volumetric (size) and gravimetric (mass) capacities of hydrogen and methane: “We are able to store huge amounts of hydrogen and methane inside pores of the MOF and store them in the vehicle tank. at lower pressures, ”said Farha.

More information: isen.northwestern.edu