Apr
28
A Fuel Cell Breakthrough
April 28, 2010 | 6 Comments
Researchers at the University of Houston and the Department of Energy’s SLAC National Accelerator Laboratory have created a new form of platinum that could be used to make cheaper, more efficient fuel cells. By tweaking platinum’s reactivity, the researchers were able to curtail the amount of platinum required by 80 percent, and hope to soon reduce it by another 10 percent, greatly trimming away at the overall cost.
University of Houston researcher Peter Strasser started in 2005 looking for ways to crack the platinum problem not by replacing platinum outright, as other researchers are seeking to do, but by making platinum more reactive. Strasser and his colleagues use a process called dealloying.
First, they combine platinum with varying amounts of copper to create a copper-platinum alloy. Then they remove the copper from the surface region of the alloy. When they test the binding properties of the dealloyed platinum-copper catalyst, they found it was much more reactive than it would be otherwise.
Dealloyed Platimun Electrocatalyst. Click image for more information.
By studying how X-rays scattered from the dealloyed samples, they were able to create detailed pictures (none seem to be posted on the internet) of the metal’s internal structure, revealing that the increased reactivity was caused by lattice strain – a phenomenon in which the arrangement of the platinum atoms is modified. By compressing the surface platinum atoms closer together, the process causes platinum atoms to bind a little more weakly to oxygen atoms and get closer to that magical “balance point” between fuel molecule dissociation and process materials catalytic binding.
Strasser said, “The distance between two neighboring atoms affects their electronic structure. By changing the interatomic distance, we can manipulate how strongly they form bonds.”
The choice of metal for the cathode is extremely important, as some metals cannot break apart the oxygen atoms while others try to bind too strongly to the oxygen atoms, taking them away from the key reaction. So, scientists are seeking the perfect “balance point,” where the number of oxygen bonds broken is maximized and the oxygen atoms bind more weakly to the catalyst. Platinum achieves the balance, which is strong enough to break the oxygen bonds but does not bind to the free oxygen atoms too strongly. Unfortunately, it also costs enough to make platinum-electrode fuel cells incredibly expensive.
Nilsson said, “This is a significant advance. Fuel cells were invented more than 100 years ago. They haven’t made a leap over to being a big (market) technology yet, in part because of this difficulty with platinum.”
Fuel cells hold significant promise because the cells are very efficient and the only byproduct is water. Current fuel cell designs can require as much as 100 grams of platinum, pushing their price tags into the thousands of dollars. Nilsson figures cutting the cost is worthwhile, “I think with a factor of ten, we’ll have a home run.”
Fuel cells and air batteries are similar. An anode provides electrons and a cathode collects them on the other end of an electrical circuit. But unlike batteries, fuel cells use hydrogen and oxygen fuel to drive their energy-producing reactions; when oxygen enters the metal cathode, it is broken down into individual atoms before it forms water with hydrogen.
The researchers next step will be to use the SSRL beam to get a closer look at the reactions between oxygen and platinum, and to determine what can be done to make the process even more efficient. The ultimate goal is to create a potential replacement not only for gasoline engines but also for the batteries found in small electronic devices.
Platinum’s big claim is the cells loaded with it are quite responsive. That could obviate some or much of the need for electron storage with batteries or capacitors. One still wonders though, even if the team gets to 90% less or just 10% of the platinum needed now will the platinum cell be economical? This is still not a defeat for those looking for lower cost alternatives.
Factually, the idea of using hydrogen as the reactive fuel might not be the best idea either. But the better fuels, methane, methanol and ethanol still function much the same way and a platinum replacement is a strong hint on what paths future research might take in these fuel’s future as well. At smaller enough platinum requirements all the potential fuels have better futures.
What would it cost to alloy and dealloy a batch? The researchers haven’t said. The description in the press releases doesn’t say, but as a mechanical process it wouldn’t be a huge thing – especially as the raw stock is platinum.
Good idea, good work – how much further can it go?
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“Cheaper Fuel cell” technology is a possiblity and we can be sure of that, it will happen in small but significant steps – very much like the evolution of the Solar PV cell. I think we need to worry more about how to generate cheap Hydrogen. Hydrogen generated by Electrolysis is costly and cannot be called as a fully “green technology”. So, if Hydrogen generation is dependent on cracking Natural Gas then we can be assured that it cannot be perpetual as Natural Gas reserves are finite. It is another matter that Natural Gas technologies also cannot be called “fully green”. So where do we get cheap and ‘green’ Hydrogen???
The answer to Mr. Kamath is use the hydrogen rich and liquid light alcohols methanol and ethanol or petroleum gasses methane on up.
I am enjoy reading and learning about fuel cell technology and advancments in this particular field. This article is very informative and I enjoyed reading it. I am looking forward to the day when batteries are replaced with less expensive alternatve energy cells, particulary at christmas when my 3 year old opens and plays with all the battery operated toys. lol
Thanks for the post…
I agree with Brian Westenhause’s comment
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