A Basic – and Slightly Acidic – Solution for Hydrogen Storage
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Image courtesy of Brookhave National Laboratory
Etsuko Fujita, Jonathan Hull, and James Muckerman
Sometimes, solutions for hard problems can turn out to be pretty basic. That's especially true for a team of researchers at the Office of Science's Brookhaven National Laboratory (Brookhaven Lab), where the solution for a hard problem they were working on turned out to be pretty basic…and also a bit acidic.
The hard problem they were working on was how to store hydrogen fuel. Hydrogen gas (H2) is a clean and powerful fuel, but it's also extremely light, which makes it difficult and costly to store. It's typically held in high pressure tanks, although researchers at another Office of Science lab recently found a possible way to keep it in naturally-formed frozen cages.
In a paper published yesterday (Sunday, March 18th) in Nature Chemistry, researchers at Brookhaven Lab led by chemist Etsuko Fujita announced that they had found a safe and reversible way to store hydrogen under mild (and therefore hopefully much more economical) conditions, using a newly developed catalyst.
Enlarge Photo
Image courtesy of Brookhave National Laboratory
This diagram shows the new catalyst in its protonated and deprotonated states as it reversibly converts hydrogen and CO2 gas to and from liquid formate or formic acid at ambient temperature and pressure. The gases can thereby be stored and transported as a liquid, and used later in carbon-neutral energy applications, simply by adjusting the pH.
Their work began by seeing acids and bases in an unconventional way – as potential carriers of hydrogen fuel. Students often learn about acids and bases as part of their science fair projects. The ‘volcanic' reaction of vinegar (a mild acid) and baking soda (a mild base) has given many students an early interest in the sciences. That was true for Jonathan Hull, a lead researcher on the paper, who was intrigued by seeing a similar reaction blow the corks off wine bottles.
However, many acids and bases are actually watery solutions filled with hydrogen. In an acidic solution, the hydrogen atoms wander free. They're usually missing their electron too, which gives them a positive charge (atoms and molecules with either a positive or a negative charge are called ions). In a basic solution, the hydrogen atoms are usually connected with something else, a negative ion of some sort. And yes, when an acid and a base react with each other, they typically create something neutral, like water.
The catalyst created by researchers at Brookhaven Lab connects hydrogen gas and carbon dioxide, "storing" the hydrogen linked to (adduct to) carbon dioxide in a mildly basic solution. The reaction can be reversed – and the hydrogen fuel released – by adding a bit of acid. The entire process can be run, and easily reversed, in a watery solution under mild temperatures and pressures with no toxic byproducts, and at a faster rate than any previous catalyst.
As a consequence, Brookhaven Lab's new catalyst might be used in future hydrogen fuel vehicles, though additional testing will be needed to see if it can be economically scaled up to industrial production. It may show up in other high powered systems too—time and technology will tell.
This new catalyst shows the best of the Office of Science and its labs at work: Researchers taking on truly challenging problems, and finding basic (and sometimes slightly acidic) solutions.
The Department's Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information about Brookhaven Lab, please go to: http://www.bnl.gov/.
Charles Rousseaux is a Senior Writer in the Office of Science.
