Science

Researchers identify new low-cost catalyst for hydrogen production

Researchers identify new low-c...
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Daniel Nocera, the Henry Dreyfus Professor of Energy and Professor of Chemistry (Image: Donna Coveney)
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Daniel Nocera, the Henry Dreyfus Professor of Energy and Professor of Chemistry (Image: Donna Coveney)

To make sunlight practical as a dominant source of energy a viable storage technology needs to be developed. One promising area of research is imitating the process of photosynthesis to separate the hydrogen and oxygen atoms in water to create hydrogen fuel. An MIT team led by Daniel Nocera is now reporting that nickel borate can efficiently and sustainably function as the oxygen-producing electrode in such a process, bringing the dream of energy storage systems that would allow buildings to be completely independent and self-sustaining.

Like many people, Nocera, the Henry Dreyfus Professor of Energy and Professor of Chemistry at MIT, believes that solar energy is the only feasible long-term way of meeting the world’s ever-increasing needs for energy. That is why he has focused his research on the development of an efficient way to split water using electricity that could form the basis for new energy storage systems. The systems would use energy from intermittent sources like sunlight or wind to create hydrogen fuel, which could then be used in fuel cells or other devices to produce electricity or transportation fuels as needed.

Nocera pictures small-scale systems in which rooftop solar panels would provide electricity to a home, and any excess would go to an electrolyzer to produce hydrogen, which would be stored in tanks. When more energy was needed, the hydrogen would be fed to a fuel cell, where it would combine with oxygen from the air to form water, and generate electricity at the same time.

For such systems to become viable they must be cheap and reliable. So Nocera has concentrated on the development of less-expensive, more-durable materials to use as the electrodes in devices that use electricity to separate the hydrogen and oxygen atoms in water molecules.

Now, along with postdoctoral researcher Mircea Dincă and graduate student Yogesh Surendranath, he is reporting the discovery of yet another material that can efficiently and sustainably function as the oxygen-producing electrode. This time the material is nickel borate, made from materials that are even more abundant and inexpensive than an earlier cobalt-based electrode.

Even more significantly, Nocera says, the new finding shows that the original compound was not a unique, anomalous material, and suggests that there may be a whole family of such compounds that researchers can study in search of one that has the best combination of characteristics to provide a widespread, long-term energy-storage technology.

“Sometimes if you do one thing, and only do it once,” Nocera says, “you don’t know - is it extraordinary or unusual, or can it be commonplace?” In this case, the new material “keeps all the requirements of being cheap and easy to manufacture” that were found in the cobalt-based electrode, he says, but “with a different metal that’s even cheaper than cobalt.”

But the research is still in an early stage. “This is a door opener,” Nocera says. “Now, we know what works in terms of chemistry. One of the important next things will be to continue to tune the system, to make it go faster and better. This puts us on a fast technological path.” While the two compounds discovered so far work well, he says, he is convinced that as they carry out further research even better compounds will come to light. “I don’t think we’ve found the silver bullet yet,” he says.

John Turner, a research fellow at the National Renewable Energy Laboratory in Colorado, calls this a nice result, but says that commercial electrolyzers already exist that have better performance than these new laboratory versions. “The question then is under what circumstances would this system provide some advantage over the existing commercial systems,” he says. For large-scale deployment of solar fuel-producing systems, he says, “the big commercial electrolyzers use concentrated alkali for their electrolyte, which is OK in an industrial setting were engineers know how to handle the stuff safely; but when we are talking about thousands of square miles of solar water-splitting arrays, and individual homeowners, then an alternative electrolyte like this benign borate solution may be more viable.”

The original discovery has already led to the creation of a company, called Sun Catalytix, which aims to commercialize the system in the next two years. The latest research findings appear in the journal Proceedings of the National Academy of Science (PNAS).

19 comments
BoilingOil
Ah, so now we use solar cells to produce electricity, with which we split water atoms into oxygen and hydrogen. And then later, we burn the hydrogen to AGAIN produce electricity, which we use for all kinds of other stuff...
I\'m wondering: every conversion costs an amount of energy, causing the efficiency to drop. So why transform electricity into hydrogen, and then back again? Wouldn\'t it be smarter to just skip the last two conversions, and just store the electricity directly? What do we stand to gain from these extra conversions?
jimyoung
Boiling Oil, what we gain is storage capability, portability, and slow accumulation/fast release capability. I don\'t think we need to compete on overall efficiency since there is generally less impact from the inefficiencies related to hydrogen than fossil fuels.
There are concerns about catalysts and storage chemistry/release rates that do merit concern, but they must be compared to the existing fuels and their dependence on a much larger infrastructure that limits our ability to operate independently, especially during natural disasters, etc. Rational safety factors may decrease overly shortsighted, purely economic, efficiency, but that has been true with every previous energy source I can think of.
Dimitri Leontari
Batteries tend to be expensive to produce, dirty, and lose their efficiency over time. Efficient hydrogen production has been sought after to take the place of batteries as a storage solution. Your name says is all boiling (heating) oil or heating salt are two other methods used to store energy produced by solar at times when the sun isn\'t out. The problem with hydrogen production has been older catalysts are expensive made from platinum. This is a cheaper way to get the job done.
dave_larson
You don\'t burn the hydrogen Dummy!! Use it in a fuel cell... For a super clean energy source when the sun isn\'t shining.
fatfox
BoilingOil: Could you give an example of a way to \'store the electricity directly\'? Maybe I\'m dumb, but it\'s not a phrase that is making any sense to me.
windykites
Surely the best way is to feed surplus energy back into the grid, which is credited to your account. You don\'t need to store it. That\'s what we do in the UK.
Aloysius
fatfox-I think he means batteries. That point is addressed by jimyoung and Dimitri Leontari
jeffbloggs
It would be good if multiple conversions were not required to have readily available energy. Boilingoil, you are correct in assuming that most mechanical, electrical and biological systems conform to the second law of thermodynamics in that they always tend to increase entropy (or decrease the efficiency of conversion), this tends to be especially so if multiple conversions are involved. However energy conversion problems or efficiencies are generally confined to specific input to “desired” output conversions. The trick to sustainability is to reuse every output from the conversion process to increase overall “efficiency”. For example: a CHP (Combined Heat Power Generator) that converts methane (NG) into electricity at up to 47% eff. and that reclaims the heat from the exhaust/cooling system to warm buildings, the total efficiency can be up to 90%. Now if you use a biogas system to create the methane through anaerobic digestion you can use nearly any waste organic matter (including that from landfill etc) to produce a gaseous fuel that can be stored and compressed for use in vehicles or generation, using existing Natural Gas equipment. Anaerobic digestion is a naturally occurring phenomenon that consumes organic material (or Carbohydrates) and converts them to methane (Hydrocarbons), with the only process waste being pathogen free soil improving mulch. The beauty of this process is that it rides piggy back on human consumption ie more food consumption = more organic waste. Also it uses organic (plant or animal waste) waste that is no longer fit for human consumption, unlike biodiesel, ethanol etc. But I suppose the best thing is that organic material is solar powered through photosynthesis, and plants and animals store this energy chemically, in the form of carbohydrates and fats until it can be released in the biogas system. Might seem like a lot of conversions to achieve the desired output, but along the way it produces numerous benefits to the environment and humanity. It is my opinion that hydrogen and any of its derivatives are products of fossil fuel focused development, for the exploitation of many for the benefit of a few...in this case they are obviously 'playing' with the figures to keep their 'efficiencies' high ;)
@ fatfox Capacitors will do this with a relatively low energy density, a battery obviously stores the energy chemically though
warren52nz
Boiling Oil. Electricity is an \"instant\" thing like light. You can\'t store light by shining it into a box all day then closing the lid. A capacitor stores electrons directly but storing a significant amount is impractical. So electricity needs to be converted into something else to store it. Like chemical energy or heat.... or hydrogen.
felix
fatfox:
duh! Just shovel it into a skip! XD