Researchers developing novel materials for hydrogen storage
Researchers at the Lawrence Berkeley National Laboratory are working to make hydrogen a more practical fuel for vehicles by synthesising novel materials with high hydrogen adsorption capacities.
The Berkeley team was recently awarded $2.1million in funding for the three year project, which is being undertaken in collaboration with the National Institute of Standards and Technology (NIST) and General Motors.
"We're working on materials called metal-organic frameworks (MOFs) to increase the capacity of hydrogen gas in a pressure cylinder, which would be the fuel tank," said Jeffrey Long, a Berkeley Lab scientist and co-leader of the project. "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."
MOFs are three dimensional, sponge-like framework structures that are composed primarily of carbon atoms and are extremely lightweight. "What's very special about these materials is that you can use synthetic chemistry to modify the surfaces within the materials and make it attractive for hydrogen to stick on the surface," Long explained.
Currently, vehicles using hydrogen fuel cells can achieve a range of close to 300 miles, but only if the hydrogen is stored at extremely high pressures. As well as being expensive and potentially unsafe, it is also energy intensive to pressurise the hydrogen.
So far Long and his team have succeeded in more than doubling hydrogen capacity, but only at very low temperatures. "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," he said. "We have an idea of what kinds of frameworks we might make to do this."
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. "Our approach has been to make some of the first MOFs that have exposed metal cations on the surface," he said. "Now we need to figure out ways of synthesising 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."
