Berkeley Lab developing novel metal-organic framework materials for high-capacity hydrogen storage

27 January 2012

Lawrence Berkeley National Laboratory (Berkeley Lab) is working to synthesize novel metal-organic framework materials with high hydrogen adsorption capacities sufficient to provide safe and cost-effective storage that could support a 300-mile (483-km) range on vehicles.

The US Department of Energy recently awarded Berkeley Lab a three-year, $2.1 million grant for the project, which will also include contributions by the National Institute of Standards and Technology (NIST) and General Motors (GM). (Earlier post.) The grant was part of more than $7 million awarded by DOE last month for hydrogen storage technologies in fuel cell electric vehicles.

With these materials, we’re working on storing the hydrogen without the use of very high pressures, which will be safer and also more efficient without the significant compression energy losses.

—Jeffrey Long, project co-leader

Separately, Long is also using MOFs in a carbon capture project, in which the material would selectively absorb carbon dioxide over nitrogen. For the fuel cell project, the trick lies not in getting the MOF to select hydrogen out of a mixture but to store as much hydrogen as possible.

Long’s approach is to create frameworks with lightweight metal sites on the surface, making it attractive for hydrogen molecules to bind to the sites. So far Long has succeeded in more than doubling hydrogen capacity, but only at very low temperatures (around 77 Kelvin, or -321 °F).

It’s still very much basic research on how to create revolutionary new materials that would boost the capacity by a factor of four or five at room temperature. We have an idea of what kinds of frameworks we might make to do this.

Our approach has been to make some of the first metal-organic frameworks that have exposed metal cations on the surface. Now we need to figure out ways of synthesizing the materials so that instead of one hydrogen molecule we can get two or three or even four hydrogen molecules per metal site. Nobody’s done that.

—Jeffrey Long

Martin Head-Gordon, a Berkeley Lab computational chemist an co-leader, will work on theoretical understanding of MOFs so that he can try to predict their hydrogen storage properties and then instruct Long’s team as to what kind of material to synthesize.

The scientist at GM will aid in providing accurate high-pressure measurements. The NIST scientist is an expert in neutron diffraction and neutron spectroscopy, which will allow Long and his team to pinpoint where exactly the hydrogen is going and verify that it is binding to the metals.