Polymer-dipped carbon nanotube catalysts equal or outperform platinum catalysts in fuel cells; potential for significant cost reduction
22 March 2011
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| Illustration of charge transfer process and oxygen reduction reaction on PDDA-CNT [poly(diallyldimethylammonium chloride)-carbon nanotube]. Credit: ACS, Wang et al. Click to enlarge. |
Researchers at Case Western University have developed catalysts made of carbon nanotubes dipped in a polymer solution that equal the energy output and otherwise outperform platinum catalysts in fuel cells. A paper on their work is published in the Journal of the American Chemical Society.
The team led by Liming Dai, a professor of chemical engineering, is certain they can boost the power output and maintain the other advantages by matching the best nanotube layout and type of polymer. They’ve already shown the simple technique can significantly reduce fuel cell cost. While platinum, which represents at least a quarter of the cost of fuel cells, currently sells for about $65,000 per kilogram, the researchers say their activated carbon nanotubes cost about $100 per kilogram.
Dai and research associates Shuangyin Wang and Dingshan Yu found that by soaking carbon nanotubes in a water solution of the polymer poly(diallyldimethylammoniumn chloride) (PDDA) for a couple of hours, the polymer coats the nanotube surface and pulls an electron partially from the carbon, creating a net positive charge.
Having a strong electron-withdrawing ability, poly(diallyldimethylammonium chloride) (PDDA) was used to create net positive charge for carbon atoms in the nanotube carbon plane via intermolecular charge transfer. The resultant PDDA functionalized/adsorbed carbon nanotubes (CNTs), either in an aligned or nonaligned form, were demonstrated to act as metal-free catalysts for oxygen reduction reaction (ORR) in fuel cells with similar performance as Pt catalysts.
—Wang et al.
They placed the nanotubes on the cathode of an alkaline fuel cell. There, the charged material acts as a catalyst for the oxygen-reduction reaction (ORR) that produces electricity while electrochemically combining hydrogen and oxygen. In testing, the fuel cell produced as much power as an identical cell using a platinum catalyst.
The activated nanotubes also last longer and are more stable, the researchers said. Unlike platinum, the carbon-based catalyst doesn’t lose catalytic activity and, therefore, efficiency, over time; isn’t fouled by carbon monoxide poising; and is free from the crossover effect with methanol. Methanol, a liquid fuel that’s easier to store and transport than hydrogen, reduces activity of a platinum catalyst when the fuel crosses over from the anode to the cathode in a fuel cell.
...we have demonstrated that certain polyelectrolyte (e.g., PDDA) functionalized carbon nanotubes, either in an aligned or nonaligned form, could act as metal-free electrocatalysts for ORR. It is notable that the PDDA adsorbed vertically aligned CNT electrode possesses remarkable electrocatalytic properties for ORR—similar to that of commercially available Pt/C electrode but a better fuel selectivity and long-term durability. Furthermore, this work clearly indicates that the important role of intermolecular charge transfer to ORR for nitrogen-free carbon nanotubes can be applied to other carbon materials for the development of various other metal-free efficient ORR catalysts for fuel cell applications, even new catalytic materials for applications beyond fuel cells. Therefore, the methodology developed in this study could serve as a general approach to the development of various metal-free catalysts.
—Wang et al.
The new process builds on the Dai lab’s earlier work using nitrogen-doped carbon nanotubes as a catalyst. In that process, nitrogen, which was chemically bonded to the carbon, pulled electron partially from the carbon to create a charge. Testing showed the doped tubes tripled the energy output of platinum.
Dai said the new process is far simpler and cheaper than using nitrogen-doped carbon nanotubes and he’s confident his lab will increase the energy output as well.
Resources
Shuangyin Wang, Dingshan Yu, Liming Dai (2011) Polyelectrolyte Functionalized Carbon Nanotubes as Efficient Metal-free Electrocatalysts for Oxygen Reduction. Journal of the American Chemical Society doi: 10.1021/ja1112904
Tremendous progress! I especially like the fact that these should work fine with methanol, much easier to handle than hydrogen, which would avoid the need for expensive pressurised tanks.
Posted by: Davemart | 22 March 2011 at 12:34 PM
"While platinum, which represents at least a quarter of the cost of fuel cells, currently sells for about $65,000 per kilogram, the researchers say their activated carbon nanotubes cost about $100 per kilogram.", but will they last? Will a 100kw FC ever be under $10k? Will H2 ever be effectively/economically store-able? Will oil firms successfully rig an H2 infrastructure after they've gouged all available oil?...
Posted by: kelly | 22 March 2011 at 01:48 PM
If they come out with an affordable fuel cell which works with methanol, they may even make fuel cells successful.
Methanol is much-much easier to handle.
Sounds like a HUGE discovery for the fuel-cell crowd.
Posted by: soltesza | 22 March 2011 at 02:12 PM
This could become a win=win solution to lower the initial cost and the on-going operation cost of fuel cells.
Fuel cells my not be dead yet.
Posted by: HarveyD | 22 March 2011 at 02:13 PM
Hi kelly.. yes fuel cells will go under 10k per 100 kw.. most designs now could do that easy if they were simply produced in batches of 500k the material costs arnt that high.
But thats current fuel cell designs.. newer ones reach almost the same need for platinum as current cars.. in this case 9 or so grams per car.
In fact its highly likely by 2025 a fuel cell car would have LESS platinum them a conventional car.
As for storable... they are mass producing pressure tanks for various industries right now using various techs such as dry tape winding and so on to make them far cheaper then older tanks... The tanks arnt realy all that spendy we just want better and have the power to try and get better before we go big.
As for the h2 inf... they have calced the numbers and it will only require 4% of the gross from h2 sales to grow the entire thing within 40 years. So its gona work. In fact its likely cheaper then finding more oil is now.
Oh and on lasting.. they already are nworking on fuel cell stacks that will last 60000 hours... thats over a million miles.... By the time we need to care the fuel cells will be more then durable enough to do the job and then some.
Posted by: wintermane2000 | 22 March 2011 at 02:23 PM
@kelly asked 'Will they last?
You seem to have somehow missed the bit in the article where they deal with this, and in fact most of the article:
'The activated nanotubes also last longer and are more stable, the researchers said. Unlike platinum, the carbon-based catalyst doesn’t lose catalytic activity and, therefore, efficiency, over time; isn’t fouled by carbon monoxide poising;'
Posted by: Davemart | 22 March 2011 at 02:24 PM
Methane filling station technology and costs:
http://www.methanol.org/fuelcell/special/stationcosts.pdf
Note that this is a 1999 paper, and so present costs will differ, but the conclusion is robust that the cost of building the infrastucture would be modest, far lower than for hydrogen.
Posted by: Davemart | 22 March 2011 at 02:53 PM
I just did some (very) rough calculations on the fuel costs of running a fuel cell car on methanol.
Here are is the energy per kg:
http://hypertextbook.com/facts/2005/JennyHua.shtml
And the weight per litre:
http://wiki.answers.com/Q/Weight_of_methanol_per_litre
With a US gallon at about 3.8 litres then I reckon that you have maybe 18kwh/gallon available.
At a 70% efficiency you get around 13kwh out.
At 3 miles/kwh that is around 40 miles/litre.
Methanol costs around $4/gallon and can be made from natural gas, coal or by electrolysis using a CO2 source.
It all sounds pretty similar to the costs of running a conventional car.
I'd like to see a fuel cell car having a 12kwh or so battery, so that running costs would be much reduced by using electricity at 10 cents/kwh or so for short runs rather than the 30 cents kwh this implies.
The German obsession with fuel cells is also explained by this, as their electricity due to their infatuation with renewables cost them 30 cents/kwh anyway.
Posted by: Davemart | 22 March 2011 at 03:24 PM
Should be 40 miles/US gallon, not 40 miles/litre
Posted by: Davemart | 22 March 2011 at 03:31 PM
If cost effective versatile fuel cells can be made available to the (electric) trtansport industry and also to power generation, then we could expect a seperation from the problematic internal combustion era.
It would be possible to seperate and collect the waste products like CO2 at the point of use for collection and proper disposal or reuse.
In combination with battery development and diversified hydrocarbon enrgy sources including renewable (biofuels) and synthesised offerings, practical fuel cells will be an enabling technology.
Imagine a rnge of 'drop in' cell configurations - the rest of the plant I.E. batteries and E motors being generic is elegant in concept.
The evidence of human ingenuity from artificial diamonds, carbon fibres, printed scaffolding including body parts should bolster our confidence in the viability of what is possible.
The practical applications from the new technological or physical innovative concepts and scienctific application have brought fantastic concepts towards a practical reality.
However the nano technology is known also to have many health related concerns the extent of which this can affect not just those who work in the industry but also the potential for causing unpredicted tradgedy in the world outside the lab.
These new sciences are critical to development and sustainability but environmental safeguards have as much iportance.
Posted by: Arnold | 22 March 2011 at 04:29 PM
Lets see the data after scalue up to pilot scale. And how much longer did they last; do platnium cells have lasting issues??
Posted by: riven | 23 March 2011 at 12:58 AM
@riven:
Yes, conventional fuel cells have issues with longevity, which are however being overcome.
As for how long these last:
'Unlike platinum, the carbon-based catalyst doesn’t lose catalytic activity and, therefore, efficiency, over time;'
Posted by: Davemart | 23 March 2011 at 02:32 AM
Daimler had NECAR with an on board methanol reformer that went across the U.S. years ago. Whether you reform on board or use a methanol fuel cell, it can be done. If methanol sells for $2 per gallon retail and you get 40 mpg then that is 5 cents per mile, which is not bad at all.
The last estimates I saw were about $50,000 per pump to convert to dispensing methanol. There are over 200,000 gasoline pumps in the U.S. and about 2000 are ethanol and less than 200 are methanol. California showed that you can run M85 in fleets of cars with great success in the 1980s. This can be done, but will it?
Posted by: SJC | 23 March 2011 at 06:37 AM
"Hi kelly.. yes fuel cells will go under 10k per 100 kw.. most designs now could do that easy if they were simply produced in batches of 500k the material costs arnt that high..." - I've seen no references to this.
"Within five years" has been the schedule that launched a thousand fuel cell research handouts for forty years.
Posted by: kelly | 23 March 2011 at 06:39 AM
The old joke is that fuel cells are just five years away every five years. One of these times it may just surprise everyone and investors will be scrambling to get a piece of it. Past behavior can be a future predictor.
Posted by: SJC | 23 March 2011 at 07:46 AM
I am surprised no one has mentioned using this for CHP applications. I would think reducing the cost of fuel cells could make in-home CHP practical to develop distributed power generation and use of mini-grids. Japan will probably be looking at that, given their recent experience.
Posted by: JMartin | 23 March 2011 at 08:35 AM
Progress on home fuel cells, not including this advance:
'"If the price falls again still, its popularity will gain momentum," general manager of Panasonic's fuel cell project, Mr Yasumasa Kurosaki, told the BBC. He added that the company aimed at fixing the per-unit price at around 500,000 yen, and get it even lower in the near future.
With economies of scale, Panasonic says, such devices could be competitively priced at around a couple of thousand of pounds by 2013.
"With over 40,000 hours running time already logged, we have proven the safety, reliability and CO2 savings of our devices in the real world while sales are improving gradually. We expect next year's sales to be up 20-30% on the last fiscal year," he said. '
http://news.bbc.co.uk/1/hi/sci/tech/8563928.stm
Posted by: Davemart | 23 March 2011 at 08:48 AM
There have also been interesting developments in methanogenesis in the last few years that would fit this energy paradigm. So the idea of green, renewable methanol isn't an outlandish idea long term.
Posted by: dahcredyns | 23 March 2011 at 09:13 AM
I don't know where you are getting methanol for $2/gallon.
Prices I have seen centre on $4/gallon.
Posted by: Davemart | 23 March 2011 at 09:16 AM
Natural gas is 40 cents per therm wholesale and it takes about two therms to make one gallon of methanol. Show me your $4 per gallon for methanol.
North America (Valid March 1 - 31, 2011)
Methanex Non-Discounted Reference Price USD 1.28/Gal*
http://www.methanex.com/products/methanolprice.html
Wholesale price for gasoline is about $3 per gallon with retail in the U.S. above $3.50 per gallon.
Posted by: SJC | 23 March 2011 at 09:54 AM
SJC:
Looks like you are correct - a google yesterday was kicking up much higher prices, but I did not spend a lot of time on it.
Obviously that transforms the economics of methanol fuel cell vehicles, and there would not be an awful lot in it between using grid electric or using methanol in a fuel cell.
Of course though, we don't have the efficiency of the fuel cell, and I am only guessing 70%.
Many thanks for the correction.
Posted by: Davemart | 23 March 2011 at 10:14 AM
Kelly I got the numbers from this very site over the years.. remember 10k and under is under 100 bucks per kw output and they have been talking reaching 30.. with many designs already between 79 and 45 per kw. But again in mass production 500k a year.
As for the always 5 years away... fuel cells have always been 5 years away because they were an emergency if all else fails.. as in if ww3 happens or if the suadi fields pancake.. or if saddam had managed to goad isreal into invading... or whatever...
Back in the 50s it was iff all hell breaks loose a bazzillion dollar manahatten project would make fuel cell cars in just 5 years.. to keep vital services working no matter what.
In the 70s it was a trillion dollar not so manhatten project would have resulted in fuel cell cars again for vital needs..
In the 90s... it was a many 100s of billions project biut now not just for vital needs it also would handle the wealthy..
Then bush changed everything. It is now a 10s of billions project that would replace a good third of all the cars on the road.. the ones bevs wouldnt manage due to energy needs or space problems or weaight issues or whatever...
And now its just plain comming simply because its getting cheap enough it will just come anyway even if nothing bad happens at all.
Posted by: wintermane2000 | 23 March 2011 at 10:23 AM
Most of the criticisms now being levelled at fuel cell cars are the same as those that were made against battery cars for 100 years, so it is a bit weird when battery advocates use them.
Battery cars were much delayed too.
So how confident can we be that we will see fuel cell cars on sale in around 2015 for about the $50,000 that people like Hyundai say?
The answer is pretty confident. Previously there were technological hurdles to be overcome, but we are now for a hydrogen fuelled car pretty much past that and into production engineering.
The cost department is then going to be given the job of working out costs and prices at different production volumes, and the boss will be pretty annoyed if they are more than 10% or so out.
I'd rather see high temperature fuel cells or this methanol one, but there is no serious doubt in my mind now that a basic PEM hydrogen car can be done at around the prices projected in about 4-5 years.
Posted by: Davemart | 23 March 2011 at 11:01 AM
wintermane2000,
Let's pretend ".. While platinum, which represents at least a quarter of the cost of fuel cells, currently sells for about $65,000 per kilogram, the researchers say their activated carbon nanotubes cost about $100 per kilogram."
and
"the carbon-based catalyst doesn’t lose catalytic activity and, therefore, efficiency, over time; isn’t fouled by carbon monoxide poising; and is free from the crossover effect with methanol. Methanol, a liquid fuel that’s easier to store and transport than hydrogen, reduces activity of a platinum catalyst when the fuel crosses over from the anode to the cathode in a fuel cell." is true.
What does a methanol fuel cell typically cost?
The http://www.oorjaprotonics.com/products/oorjapacmodelIII.html sells for $16,000USD.
Now the price is reduced by about 25% to $12,000 for a on-the-market ONE horsepower fuel cell.
How many horsepower do you want? I'll hold your cash.
Posted by: kelly | 23 March 2011 at 01:12 PM
@kelly,
you are really determined to dislike this technology, aren't you?
You started by not even reading the article properly, as it went against your prejudices, and now you have moved on to looking at the price of an early model as though any reduction in cost is not possible.
Well that is really the way technology works, kelly, and there are innumerable products which have gone through cost reduction cycles.
Now I don't know whether this one will be a success or not, but I am prepared to give it a chance as it holds great potential.
Posted by: Davemart | 23 March 2011 at 01:25 PM