RICHLAND, Wash. -- Like a hungry diner ripping open a dinner roll, a fuel cell catalyst that converts hydrogen into electricity must tear open a hydrogen molecule. Now researchers have captured a view of such a catalyst holding onto the two halves of its hydrogen feast. The view confirms previous hypotheses and provides insight into how to make the catalyst work better for alternative energy uses.
This study is the first time scientists have shown precisely where the hydrogen halves end up in the structure of a molecular catalyst that breaks down hydrogen, the team reported online April 22 in Angewandte Chemie International Edition. The design of this catalyst was inspired by the innards of a natural protein called a hydrogenase enzyme.
"The catalyst shows us what likely happens in the natural hydrogenase system," said Morris Bullock of the Department of Energy's Pacific Northwest National Laboratory. "The catalyst is where the action is, but the natural enzyme has a huge protein surrounding the catalytic site. It would be hard to see what we have seen with our catalyst because of the complexity of the protein."
Ironing Out Expense
Hydrogen-powered fuel cells offer an alternative to burning fossil fuels, which generates greenhouse gases. Molecular hydrogen -- two hydrogen atoms linked by an energy-rich chemical bond -- feeds a fuel cell. Generating electricity through chemical reactions, the fuel cell spits out water and power.
If renewable power is used to store energy in molecular hydrogen, these fuel cells can be carbon-neutral. But fuel cells aren't cheap enough for everyday use.
To make fuel cells less expensive, researchers turned to natural hydrogenase enzymes for inspiration. These enzymes break hydrogen for energy in the same way a fuel cell would. But while conventional fuel cell catalysts require expensive platinum, natural enzymes use cheap iron or nickel at their core.
|Contact: Mary Beckman|
DOE/Pacific Northwest National Laboratory