The record-breaking catalyst stuffs electrons - the backbone of electricity, seen here as yellow balls or yellow halos - into chemical bonds between hydrogen atoms (H) stolen from water. It uses inexpensive nickel (Ni) to do so, instead of the more common and expensive platinum.
RICHLAND, US: Looking to nature, researchers have used a common protein to guide the design of a material that can make energy-storing hydrogen gas. The synthetic material works 10 times faster than the original protein found in water-dwelling microbes, the researchers report in the August 12 issue of the journal Science, clocking in at 100,000 molecules of hydrogen gas every second.
This step is just one part of a series of reactions to split water and make hydrogen gas, but the researchers say the result shows they can learn from nature how to control those reactions to make durable synthetic catalysts for energy storage, such as in fuel cells.
In addition, the natural protein, an enzyme, uses inexpensive, abundant metals in its design, which the team copied. Currently, these materials, rely on expensive metals such as platinum.
“This nickel-based catalyst is about a hundred times faster than the previous catalyst record holder. And from nature, we knew it could be done with abundant and inexpensive nickel or iron,” said Co author, Morris Bullock of the Department of Energy’s Pacific Northwest National Laboratory.
Bullock and his colleagues want to take advantage of the closer packing available in chemicals. “We want to store energy as densely as possible. Chemical bonds can store a huge amount of energy in a small amount of physical space,” said Bullock, Director of the Center for Molecular Electrocatalysis at PNNL. The team also included visiting Researcher, Monte Helm from Fort Lewis College in Durango.
In this study, the researchers looked at only one small part of splitting water into hydrogen gas, like fast-forwarding to the end of a movie.
With a set plan in mind, the team built potential catalysts and tested them. On their first try, they put a bunch of pendant amines around the nickel centre, thinking more would be better. Since it didn’t work fast they trimmed it.
Testing a trimmed catalyst, the team found it performed much better than anticipated. Since most real-life applications will have water around, they added water to the reaction. The catalyst ran three times as fast than without water, creating more than 100,000 hydrogen molecules every second.
However, their is fast, but not efficient. The catalyst runs on electricity and requires more electricity than practical - overpotential.
Bullock said the team has some ideas on how to reduce the inefficiency. Also, future work will require assembling a catalyst that splits water in addition to making hydrogen gas. Even with a high overpotential, the researchers see high potential for this catalyst.
Also Michael Stewart, M Rakowski DuBois, Daniel DuBois, ‘A Synthetic Nickel Electrocatalyst With a Turnover Frequency Above 100,000 s-1 for H2 Production,’ contributed to this research cited in Science, August 12, 2011.
© Pacific Northwest National Laboratory News