New iron-based catalyst is fuel cell breakthrough
Researchers have created an iron-based catalyst to convert hydrogen into electricity that could dramatically lower the cost of fuel cells
The creation of the first iron-based catalyst to converts hydrogen directly to electricity has moved affordable fuel cells one step closer.
Researchers at the Center for Molecular Electrocatalysis at the US Department of Energy's Pacific Northwest National Laboratory have outlined their discovery in the latest issue of Nature Chemistry.
"A drawback with today's fuel cells is that the platinum they use is more than a thousand times more expensive than iron," said chemist R. Morris Bullock, who leads the research.
His team has been developing catalysts that use cheaper metals such as nickel and iron and now they have found one that can split hydrogen as fast as two molecules per second, with an efficiency approaching those of commercial catalysts.
Hydrogen fuel cells work by breaking the bond within a hydrogen molecule, where two electrons connect two hydrogen atoms like a barbell.
Most fuel cells use a platinum catalyst – essentially a chunk of metal – to crack a hydrogen molecule open like an egg so the electron whites run out and form a current an electric current.
Because platinum's chemical nature gives it the ability to do this chemists can't simply replace the expensive metal with the cheaper iron or nickel, but instead Bullock and his PNNL colleagues, chemists Tianbiao "Leo" Liu and Dan DuBois have taken inspiration from an enzyme called hydrogenase which uses iron to split hydrogen.
One of the properties they needed the catalyst to have was the ability to split hydrogen atoms into all of their parts by moving both the protons and electrons around in a controlled series of steps, sending the protons in one direction and the electrons to an electrode, where the electricity can be used to power things.
To do this, they need to split hydrogen molecules unevenly in an early step of the process. One hydrogen molecule is made up of two protons and two electrons, but the team needed the catalyst to tug away one proton first and send it away, where it is caught by a molecule called a proton acceptor. In a real fuel cell, the acceptor would be oxygen.
Once the first proton with its electron attracting force is gone, the electrode easily plucks off the first electron before another proton and electron are similarly removed, with both of the electrons being shuttled off to the electrode.
The speed of the team’s new catalyst peaked at about two molecules per second, thousands of times faster than the closest, non-electricity making iron-based competitor.
In addition, they determined its overpotential, which is a measure of how efficient the catalyst is. Coming in at 160 to 220 millivolts, the catalyst revealed itself to be similar in efficiency to most commercially available catalysts.
Now the team is figuring out the slow steps so they can make them faster, as well as determining the best conditions under which this catalyst performs.
"Power cuts might seem like a 1970s fad, but they could be on the way back. How can we prevent them happening again?"
- Immigration rhetoric putting off Stem students
- Flight MH370: infographics on the missing Malaysia Airlines plane
- Nasa presents Mars-landing concept for manned mission
- Flight MH370: Sonobuoy spots new signal as UK ship joins search
- ‘Heartbleed’ could affect firewalls and email systems
- Nasa to start building asteroid sample-return spacecraft
- What to Specialise in Electronics Engineering?? [03:02 am 03/04/14]
- Britain to have just one remaining coal pit by the end of 2015 [01:11 am 03/04/14]
- LV Generator Star point earthing - UK [08:35 pm 02/04/14]
- East West Rail - the Oxford to Bedford route [07:33 pm 02/04/14]
- Small nuclear power [06:06 pm 02/04/14]
The essential source of engineering products and suppliers.
Tune into our latest podcast