Stanford team reports new low-cost, non-precious metal catalyst for water splitting with performance close to platinum
22 August 2014
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| Structure of the NiO/Ni-CNT hybrid. Blue = nickel, green = nickel oxide. Credit: Gong et al. Click to enlarge. |
Researchers at Stanford University, with colleagues at Oak Ridge National Laboratory and other institutions, have developed a nickel-based electrocatalyst for low-cost water-splitting for hydrogen production with performance close to that of much more expensive commercial platinum electrocatalysts.
As described in their paper in Nature Communications, the catalyst comprises nanoscale nickel oxide/nickel heterostructures formed on carbon nanotube sidewalls (NiO/Ni-CNT nano-hybrids). The researchers were able to make the electrocatalysts active enough to split water at room temperature with a single 1.5-volt battery, said Hongjie Dai, a professor of chemistry at Stanford. This marked the first time anyone has used non-precious metal catalysts to split water at a voltage that low, he added.
Nickel (Ni) and stainless steel are typically used in industry for water reduction and oxidation catalysis respectively in basic solutions. However, Ni metal is not an ideal water reduction or hydrogen evolution reaction (HER) catalyst due to its high overpotential (~200 mV) and large Tafel slope. The state-of-art HER catalyst is platinum (Pt) and its alloys, but the scarcity and cost of Pt limit its large-scale application for electrolysis. Active and stable non-precious metal-based HER catalysts in alkaline solutions have been pursued, including Raney Ni and Nickel molybdenum (NiMo) alloy. It remains difficult to achieve both high activity and stability matching those of Pt.
Here, we report a nickel oxide/nickel (NiO/Ni) hetero-junction-like structure attached to mildly oxidized carbon nanotube (NiO/Ni-CNT) exhibiting high HER catalytic activity close to commercial Pt/C catalysts in several types of basic solutions (pH = 9.5–14). The NiO/Ni nano-hybrids is fabricated serendipitously in a low-pressure thermal annealing experiment, affording partial reduction of nickel hydroxide (Ni(OH)2) coated on oxidized CNTs that acts as an interacting substrate to impede complete reduction and aggregation of Ni.
—Gong et al.
As reported in their paper, the team built an electrolyzer that achieves ~20 mA cm−2 at a voltage of 1.5 V at room temperature, and which may be operated by a single-cell AAA alkaline battery.
The mini electrolyzer used NiO/Ni-CNT as the water reduction catalyst and a high-performance NiFe-layered double hydroxide (NiFe LDH) water oxidation catalyst. The experiment was carried out in 1 M KOH at room temperature (~23 °C) and at ~60 °C.
The kinetics and thermodynamics were greatly improved at the higher temperature, showing lower voltage of ~1.42 V at 20 mA cm-2 and higher current increase, reaching 100 mA cm-2 at a voltage of ~1.45 V with good stability. The results suggest that the NiO/Ni-CNT catalyst could match the benchmark platinum catalyst for efficient electrolyzers with ultra-low overpotential, the team concluded.
The scientists do not fully understand the mechanics of the performance of the NiO/Ni-CNT catalyst; future work will tackle this and perform in situ spectroscopic techniques to elucidate the reaction mechanisms and pinpoint the HER active sites in the NiO/Ni material. However, they suggested that the high activity of NiO/Ni-CNT was due possibly to the nanoscopic NiO/Ni interfaces in the heterostructure.
The discovery was made by Stanford graduate student Ming Gong, co-lead author of the study. The nickel/nickel-oxide catalyst significantly lowers the voltage required to split water, which could eventually save hydrogen producers billions of dollars in electricity costs, according to Gong. His next goal is to improve the durability of the device.
The researchers also plan to develop a water splitter than runs on electricity produced by solar energy.
Other authors of the study are Wu Zhou, Oak Ridge National Laboratory (co-lead author); Mingyun Guan, Meng-Chang Lin, Bo Zhang, Di-Yan Wang and Jiang Yang, Stanford; Mon-Che Tsai and Bing-Joe Wang, National Taiwan University of Science and Technology; Jiang Zhou and Yongfeng Hu, Canadian Light Source Inc.; and Stephen J. Pennycook, University of Tennessee.
Principal funding was provided by the Global Climate and Energy Project (GCEP) and the Precourt Institute for Energy at Stanford and by the U.S. Department of Energy.
Resources
Ming Gong, Wu Zhou, Mon-Che Tsai, Jigang Zhou, Mingyun Guan, Meng-Chang Lin, Bo Zhang, Yongfeng Hu, Di-Yan Wang, Jiang Yang, Stephen J. Pennycook, Bing-Joe Hwang & Hongjie Dai (2014) “Nanoscale nickel oxide/nickel heterostructures for active hydrogen evolution electrocatalysis” Nature Communications 5, Article number: 4695 doi: 10.1038/ncomms5695
Potentially transformational as hydrogen can be readily transported mixed into the natural gas grid and stored in salt caverns.
That means that solar, for instance, can be sited in the south west and the power it produces used in the north east in winter, and overbuild of solar anywhere to help mitigate seasonal variation can be put to good use.
Hydrogen blending in NG pipelines:
http://www.nrel.gov/docs/fy13osti/51995.pdf
Salt Cavern Storage:
http://www.kbbnet.de/wp-content/uploads/2011/09/Present-trends-in-compressed-air-energy-and-hydrogen-storage-in-Germany1.pdf
Posted by: Davemart | 22 August 2014 at 09:30 AM
Can sea water be used? Are we talking large volumes of water? Is desalinized water a potential byproduct of power production from hydrogen?
Posted by: Calgarygary | 22 August 2014 at 09:48 AM
An exciting development to be sure, but the inefficiencies of the energy conversion remain. I'd love to see sufficient developments to make long term storage, and long distance transport economically competitive, but it's really hard to imagine that moving atoms will ever be cheaper than moving electrons.
Posted by: electric-car-insider.com | 22 August 2014 at 09:51 AM
evi:
You can't compare electricity which isn't there when you need it to electricity which is, even if it has incurred losses in the process.
Clearly when you can you use your electricity as directly as possible, but unless we can persuade the powers that be to build out nuclear that either means using fossil fuels to produce it or using renewables and storing it.
In any case electrolysis is of the order of 70% efficient, and in Germany the process heat is used so pushing the efficiency including heat up way over 80%.
Since charging the Leaf,for instance, loses 10-20% of the electricity from the wall, we are not doing too badly.
Both transport and storage of hydrogen is very efficient, and the efficiency of compression is coming down towards 95% efficient:
http://www.hydrogen.energy.gov/pdfs/review12/pd048_lipp_2012_o.pdf
Everything is lossy, that is thermodynamics for you, the question is are the losses low enough to cope with?
Since FCEVs work very well as a PHEV and so electricity when available for direct use could still be so used, this would seem to be all gain with no downside to me.
Posted by: Davemart | 22 August 2014 at 10:06 AM
Gary,
I doubt sea water can be used, they probably use PEM electrolyzers which require distilled water with an alkaline additive. Water that comes out of a fuel cell could be used, but 60% of the sea water to fresh water is created by using multi stage condensers on power plant cooling sections.
Posted by: SJC | 22 August 2014 at 10:52 AM
@CalgaryGary:
I did the sums once ages ago, and we are talking about substantial but not huge amounts of water, as the water is in no way used up, but simply processed and recycled.
I have no idea if salt water could be used.
Presumably you would not use that at first anyway, to avoid any problems from the salt.
The initial problem is increasing the durability of the catalyst, so lets solve that first!
I don't see the connection with desalination.
Posted by: Davemart | 22 August 2014 at 10:53 AM
Davemart> You can't compare electricity which isn't there when you need it to electricity which is, even if it has incurred losses in the process.
You have a good point. So the question is, what is the best way to create zero carbon energy supply? Best as in most economic, because it's unlikely to win if it is substantially more expensive.
I'm not opposed to H2 per se, I just think it is unlikely to be a competitive transportation fuel. I also believe we are much more likely to have hi-efficiency transmission lines before we have high efficiency hydrogen pipelines.
Several kinds of technology breakthroughs would quickly change my mind. But until they happen, I'll place my bets on the "near targets" of solar, wind, hydrothermal, hydro (including pumped hydro, which currently provides 5% of California grid capacity) and cheaper battery grid storage.
Those do not provide a 100% solution, but they are here now and put us on a path of meeting viable targets.
Perhaps most importantly, several of them allow consumers to vote with their wallets - today.
Posted by: electric-car-insider.com | 22 August 2014 at 11:49 AM
Desalinating seawater only takes a small fraction of the energy it takes to split the same volume it into hydrogen, so if necessary, it will only decrease the efficience a little.
The amount of water needed for all your transportation needs is much smaller than what you use to flush your toilet.
5kg H2 ==> 40l H2O > 1000km driving.
Posted by: Alain | 22 August 2014 at 12:00 PM
Well, evi,
We already have 'high efficiency hydrogen pipelines' as I detailed concisely in the 130 page Government study I linked to!
They are called: 'Natural gas pipelines' and they do the job just dandy.
For solar, wind, etc you either need to carry on using buckets of fossil fuels, as Germany does at the moment for instance with CO2 emissions 30% above the per capita European average, burning vast quantities of Russian gas and filthy lignite in the process, or you get involved with hydrogen for storage.
Every single scheme that I am aware of trying to put lots of renewables to use envisages or uses massive quantities of hydrogen.
It is only on blogs talking about electric cars that it is imagined that renewables can magically do the job without the use of hydrogen, and where fuel cells are seen as some kind of opposing force.
Posted by: Davemart | 22 August 2014 at 12:05 PM
Hi Alain:
I don't know about the rest of your figures, but 5kg of hydrogen aren't going to move you 1000km.
You get around 60-70miles/kg, so around 500km is more like it.
I think that you are probably looking at the 33kwh or so in 1kg of hydrogen and thinking about how far that would move a BEV, but the fuel cell still needs to convert it back to electricity at around 50% efficiency or so.
Posted by: Davemart | 22 August 2014 at 12:28 PM
Water is plentiful and cheap and soon will be H2.
With cheap and plentiful fuel (H2), FCEVs could become an interesting alternative for Extended range and cold weather EVs.
Posted by: HarveyD | 22 August 2014 at 02:11 PM
> Every single scheme that I am aware of trying to put lots of renewables to use envisages or uses massive quantities of hydrogen.
Interesting, that is not the data I am seeing, and it seems to be a rather sweeping statement.
In southern latitudes, we don't need to massively overbuild for seasonal variation. We just need to solve for day/night and wind variation. That is possible with grid storage, which appears to be fairly near term. Not just batteries like Ambri, but pumped hydro, which is in widespread use in California and solar thermal storage. Energy giant NRG is betting big on renewables, presumably David Crane has a good grasp of the viable grid mix.
I don't know what the long term renewable solution is for winter in northern latitudes where solar is not sufficient, but I'm not seeing a lot of investment in large-scale electricity to hydrogen projects. Some small scale demonstrators, yes, but nothing on scale that will make a dent in coal and gas.
Here in the states, wind (and gas) are displacing coal.
Posted by: electric-car-insider.com | 22 August 2014 at 02:29 PM
Thanks for input.
I now calculate that 1 kwh electricity generated by a fuel cell would produce about 0.4 liters of water which might be of some value if one were to bottle it for high end restaurants but on doing some research I find that even in Saudi Arabia the cost of producing desalinized water on a large scale is only about 1/3 cent per litre so the volume produced from a fuel cell would be insignificant in terms of value even in water short areas.
Posted by: Calgarygary | 22 August 2014 at 02:33 PM
Davemart, I really appreciate your posting links to interesting and worthwhile reports. But I do sometimes wonder if you read those reports or just hope that others won't, and that posting them somehow give your assertion more credibility, even when the cited work pretty much refutes your assertion. The pipeline report is a pretty good example.
We do not "already have" NG pipelines capable of transporting hydrogen, this is a proposal under consideration. The report itself says that the membranes to extract the hydrogen at the delivery end are still under development.
Cost is a huge consideration. Did you read the part about the extraction cost being $0.30 to $1.30 per kg. ouch!
Note also that they are talking about 5%-%15 concentrations of H2, meaning that you would, at best, still be on an 85% fossil fuel economy.
The report clearly says that extraction is a long term solution, not a near term one.
This report pretty much totally refutes your argument that H2 distribution by pipeline is viable, except in the long term, and at high cost.
Posted by: electric-car-insider.com | 22 August 2014 at 03:06 PM
evi:
I don't see what is sweeping at all in stating that 'every single scheme THAT I AM AWARE of uses hydrogen for storage'
That simply invites anyone who is familiar with schemes which don't to give me the reference, as I certainly don't know about every scheme.
I am talking about, for instance, the German Energiewende scheme, down to the scale of this for the Isle of Wight in the UK:
http://fuelcellsworks.com/news/2013/02/21/acta-and-ecoisland-sign-letter-of-intent-for-isle-of-wight-domestic-hydrogen-partnership/
Your idea of 'Southerly latitudes' is rather different to mine.
Anywhere much north of San Diego there is pronounced seasonal variation, which you either overbuild for, in which case why not use the surplus to generate hydrogen which will keep until the winter, or you throw it away, or you don't overbuild and you use fossil fuels.
It is impossible to cover the whole of a large subject in single posts in blogs, but essentially there is a hierarchy of storage for energy, and if you want to store lots of it you need CAES which I don't fancy as it is very dubious environmentally, or you need hydrogen.
Pumped storage is well and good (geddit?) but there ain't much energy in a lot of water lifted to a fair old height.
The classic example is Norway, where they store a lot of energy, for Scandinavia not just themselves, but can only store so much, and in droughts run into trouble.
Without a handy mountain, you have problems.
On top of that at ~80% round trip efficiency it is pretty lossy also.
Norway in its own plans puts a lot of emphasis on hydrogen.
The best overview I am aware of of the potentials and limits of storage systems is on this blog:
http://physics.ucsd.edu/do-the-math/
Posted by: Davemart | 22 August 2014 at 03:34 PM
evi:
Have I read the links I cite?
Yes, but in different depths and with different degrees of recall as many of them are pretty complex.
Some which have a lot of mathematics and so on are in their detail above my head anyway, and I don't re-read every post before citing it.
So no, I am not perfect, do not have perfect mastery of my subject, and may myself have misapprehended the content.
By citing the links, and I try as much as possible to make them the most authoritative I can but to avoid as much as possible those which are too technical unless I know that my interlocutor, such as EP here will understand more than me of the technicalities anyway, I allow people to check for themselves, and point out the bits that I have misread, misunderstood or forgotten.
I think that is pretty much the best you can expect for this sort of discussion.
To the article itself:
As I noted above, in this sort of blog I can only reasonably write so much, and also have many more references than the ones I cite, so that I tend to have on occasion amalgamated several articles in my mind.
Membranes: I did not mean to imply that every dot and comma is in place.
It could not reasonably be expected to be, since we have not used the NG system for transported hydrogen before.
You could equally well have mentioned embrittlement or several other issues, and for all of them neither you nor I would have the knowledge needed to properly evaluate them.
The report, which is written by the leaders in the field, clearly indicate though that the transport is perfectly practical, and give us an a idea of the various blends and the different costs of adapting the NG network to suit.
So at that level of technicality I simply accept their judgement as there is no point in either of us second guessing it.
However the NG network still provides the backbone of what we need without separate hydrogen in it, as natural gas can simply be reformed at the station, and a lot of the early stations will do just that, and reform on the spot, or alternatively just run in an electricity supply and electrolyse on the spot.
So the fundamental argument that much of the infrastructure is already there is it seems to me safe.
The other part about the limits on of the percentage of hydrogen does not take into account that the hydrogen does not stay in the pipelines for long, but is taken out to put in salt caverns, compressed and put in cars and so on.
In any case it is ample for early stage use, and by the time it reaches its limits, if it does, then if more or different pipelines are needed then it must be a success anyway.
There are no fundamental obstacles to building dedicated hydrogen pipelines, industry uses them all the time, but of course you don't want that cost at first, and the NG pipelines and the electricity grid mean we don't need to.
Posted by: Davemart | 22 August 2014 at 04:02 PM
Do these researchers know that I own a 2005 dodge neon ?? in 2020-22 it will be time to change my car so I have to plan my next purchase now so in due time if lucky I will have a better deal then back in 2005now the time to commercialise this electrolyzer and start producing hydrogen for fuelcell cars and also produce a surplus and put it in ice cars and trucks. In 2020 I will then buy a cheap used ice car and put low cost non-polluting hydrogen in it. This is possible to do hydrogen with wind mills and solar panels. Put the electrolizers at gas stations so no need to transport hydrogen. Do it now so prices will be cheap in 2022, it will displace petrol so petrol prices will go down.
Posted by: gorr | 22 August 2014 at 05:15 PM
@ECI & DM,
I suggest that the Keystone XL oil pipeline be cancelled and the money saved be used to build a dedicated H2 pipeline instead, connecting the desert southwest with the northeast where heating oil is still used for the winters. Just kidding...such won't be needed, since RE is available a lot closer, for example, Midwest wind, sun, and biomass.
Most other places produce enough renewable energy in spring, summer, and fall to be used for winter, so trans continental H2 pipeline won't be needed. Only local H2 piping is needed for local storage and local use, unlike fossil fuels, which must be transported thousands of miles, and no one raises objection.
Posted by: Roger Pham | 22 August 2014 at 06:04 PM
Davemart> You could equally well have mentioned embrittlement or several other issues
Ok, now I know for sure you did not read that report ;-)
(it says that H2 in NG pipelines does not present an embrittlement problem)
I appreciate the honesty of your replies Davemart.
btw, apparently shipping hydrogen by dedicated pipeline is totally non-economic. The energy cost is 4-5x that of NG. Short pipelines are in use for petrochemical production, but nothing like the trans-national pipelines we have for NG. The last IEA report I read estimated that $1 trillion would be required for a US national H2 pipeline and $700 billion for distribution (filling stations).
I'm sorry I don't have a link to a free copy of the report, but here's the paid one, maybe you can find a free version. I think you will find it authoritative, if not exhaustive (and maybe exhausting!) Definitely worthwhile if you'll be arguing these points much:
http://www.oecd-ilibrary.org/energy/prospects-for-hydrogen-and-fuel-cells_9789264109582-en
If you are ever on the US west coast, I hope you look me up so I can buy you a beer. Although I do not share your outlook, I appreciate your contribution to the discussion.
Posted by: electric-car-insider.com | 22 August 2014 at 06:07 PM
Free version:
http://web.archive.org/web/20080307082839/http://www.iea.org/textbase/nppdf/free/2005/hydrogen2005.pdf
I realize this is not very current, but it is the last version produced and still one of the most authoritative reviews of the technology available anywhere. Feel free to quote better numbers based on new tech, with sources of course.
Posted by: electric-car-insider.com | 22 August 2014 at 06:26 PM
evi:
Thanks for the link.
It looks as though I will actually have to read it, which as you point out I usually find unnecessary! ;-}
Since it is a considerable study and it is Saturday, that is not going to happen anytime soon.
However as other links I have given show, other delivery options are already costed in to the price of hydrogen.
There are plenty of hydrogen pipelines in industry, and a solution does not have to be universal to help, as major routes could be covered.
Advances in cost effectiveness are also possible in other things as well as batteries, so if we need them in volume there would possibly be good cost reductions.
On top of that if, as seems possible to me, the move is from ICE PHEV's to FCEV PHEVs the need for fuel would be substantially reduced, perhaps to very low levels if they were RE's
Hydrogen is far from the only game in town and high temperature fuel cells using just about any fuel seem to be on the cards.
Some will feel that that simply means that hydrogen infrastructure is a waste of time, and should not be built.
That would be odd from those who defend German solar, for instance, as it is said that this enabled the development of solar cells themselves for use in hotter climates.
That seems an absurd argument to me, at a cost of hundreds of billions, but the few hundred million it will take to build an initial not spot infrastructure for hydrogen is, in energy market terms, a tiny amount, and not spending it to cover the option could be a very expensive mistake.
I like batteries, and if we come up with super-duper batteries which make fuel cells in transport largely unnecessary, will be perfectly happy.
I part company though with those who think this inevitable, and grandly proclaim to that effect.
That is not what the experts are saying, and to me, just as to them, it makes sense at this stage of the game to simply cover all the bases, build what we can right now, and see how the various technologies progress.
The bottom line is that they are all better by a long way than current technology using internal combustion engines and oil.
Posted by: Davemart | 23 August 2014 at 01:48 AM
Being a nerd I have of course had a look at the link, which gets relevant on page 61.
A given diameter of pipe to to carry hydrogen being way larger than for NG is fair, but may perhaps be countered to some extent by increased pressure, although of course that worsens the leakage problem but the technology of seals etc is not static.
Their notion that hydrogen cannot be transported in the existing NG network is flatly wrong, as I have shown, and shows the age of the report, 2008 (!)
The idea that for some reason the network would have to be the same size and capacity as the existing NG network, and costs shown to match, is just nuts.
Here in the UK the vast majority of our network is to every house and business.
What on earth would you want that for?
A hydrogen network would only need to go to the petrol stations, and only the bigger ones at that as tankers etc as I detail elsewhere will cope perfectly well with the smaller ones.
Linkage would only be needed anyway for those stations which did not chose to reform/electrolyse on site.
In addition FCEV PHEVs would greatly reduce the remaining limited volume for transport.
In short in five minutes I have no problem at all in knocking an order of magnitude or so off the costs they suggest.
I am left wondering if you have actually read the report you link?:-0
I am all in favour of a spirit of disputation,but you really should have picked up and mentioned those obvious flaws.
You picked up on small areas of difficulty in the report I linked, and ignored the general thrust that transporting hydrogen in NG pipes is very doable, and here taken the erroneous and obviously flawed general conclusions of a very old report and ignore the obvious gigantic gaping holes in the detail.
You should not, in my view, allow yourself such partiality in your reading.
It leads to erroneous judgement.
Cheer your team on by all means, but like any good coach cast a cold and unenamoured eye on their performances.
Posted by: Davemart | 23 August 2014 at 02:11 AM
Those who push transport of hydrogen in the NG pipeline system need to remember two things:
1. Hydrogen has about 1/3 the volumetric energy density of methane. A Hythane stream that is 20% H2 by volume has 93% of its energy in methane, only 7% from H2.
2. Hydrogen has 1/8 the mass density of methane. This changes the physical properties of the gas stream radically as the H2 content gets significant. Pumping stations designed for natural gas will not work with high-H2 streams.
The cheapest way to make hydrogen is going to be to steam-reform fossil methane and just dump the CO2; the second-cheapest is to gasify coal. Consumers won't have any choice about how H2 is made. If you are looking for actual carbon-neutral fuel, hydrogen is probably one of the worst options.
Posted by: Engineer-Poet | 23 August 2014 at 05:31 AM
@EP:
As the links detail of course the volumetric density of hydrogen is low compared to natural gas which means that you don't shift as much for any given diameter.
The studies I cite and the trials do not however support your ex nihilo claim that the stations can't pump the gas.
What are you basing that claim on?
It is one heck of a jump anyway from that to what you are arguing, and you simply ignore umpteen alternatives.
I'd prefer not to use hydrogen but DME or whatever, but that does not mean it is impossible to make hydrogen work.
Posted by: Davemart | 23 August 2014 at 07:04 AM
DM> In short in five minutes I have no problem at all in knocking an order of magnitude or so off the costs they suggest.
:-D
Posted by: electric-car-insider.com | 23 August 2014 at 08:30 AM