Science

Nanosheet catalyst brings a hydrogen economy one step closer to reality

Wei-Fu Chen examines the atomic structure of the platinum alternative electrocatalyst
Wei-Fu Chen examines the atomic structure of the platinum alternative electrocatalyst
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Wei-Fu Chen examines the atomic structure of the platinum alternative electrocatalyst
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Wei-Fu Chen examines the atomic structure of the platinum alternative electrocatalyst
Magnification of the nickel-molybdenum-nitride catalyst, detailing the unexpected nanosheet structure
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Magnification of the nickel-molybdenum-nitride catalyst, detailing the unexpected nanosheet structure
The Brookhaven National Laboratory research team
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The Brookhaven National Laboratory research team

Harnessing the power of hydrogen gas presents one of the most promising options available for obtaining a large-scale sustainable energy solution. However, there are numerous and significant challenges present in the production of pure hydrogen, one of the most prominent of which is the high costs associated with the use of rare and expensive chemical elements such as platinum. Accordingly, the team at the Brookhaven National Laboratory set out to create a catalyst with high activity and low costs, that could facilitate the production of hydrogen as a high-density, clean energy source.

The key component in the production of pure hydrogen is one of the most abundant elements on the planet. Water provides a cheap and plentiful source and is free of harmful greenhouse gas by-products. Electrolysis, or the splitting of water (H2O) into oxygen (O2) and hydrogen (H2), requires an external source of electricity and an efficient catalyst. It's the latter of these that causes the difficulties.

An effective catalyst has to combine high catalytic activity, high durability and high surface area. The most effective material for use as the catalyst for electrolysis is platinum: a highly expensive commodity. The rising cost of platinum (currently around US$50,000 per kilogram) has gone a long way to discouraging widespread investment in the production of hydrogen gas.

However, the high cost isn't the only issue associated with use of the rare element. James Muckerman, senior chemist on the project, said “People love platinum, but the limited global supply not only drives up price, but casts doubt on its long-term viability ... There may not be enough of it to support a global hydrogen economy”.

Creating an alternative to platinum presents a significant challenge. The strength of an element's bond to hydrogen determines its level of reaction – too strong and the initial activity will poison the catalyst, too weak and there is little or no activity. “We needed to create high, stable activity by combining one non-noble element that binds hydrogen too weakly with another that binds too strongly," said Muckerman.

Magnification of the nickel-molybdenum-nitride catalyst, detailing the unexpected nanosheet structure
Magnification of the nickel-molybdenum-nitride catalyst, detailing the unexpected nanosheet structure

The new catalyst is initially made up of nickel and metallic molybdenum, but the resulting compound is still unable to match the performance levels of platinum. To solve this issue, nitrogen is introduced through a complicated procedure in which the compound is subjected to a high-temperature ammonia environment. This process infuses the nickel-molybdenum with the nitrogen, but also produces an unexpected result.

Nitrogen has been used for similar applications in the past, but only for bulk materials, or objects larger than one micrometer. When applying the element for use on nanoscale materials, with dimensions measuring billionths of a meter, the reaction transformed the resulting compound into unexpected two-dimensional nanosheets. These structures provide highly accessible reactive sites, and therefore more reacting potential. The paper's lead author, Wei-Fu Chen, comments on the resulting compound, stating that “Nitrogen has made a huge difference – it expanded the lattice of nickel-molybdenum, increased its electron density, made an electronic structure approaching that of noble metals, and prevented corrosion."

The Brookhaven National Laboratory research team
The Brookhaven National Laboratory research team

The combined cost of the components required for the compound is about one one-thousandth that of platinum, but with a comparable (though slightly lower) performance level. The production process is also simple and scalable, making it viable for industrial applications.

Although this new compound falls short of providing a complete solution to the multi-faceted challenge of creating affordable hydrogen gas, it does provide a significant reduction in the cost of the required materials. “We needed to figure out fundamental approaches that could potentially be game-changing, and that's the spirit in which we're doing this work," said Muckerman. "It's about coming up with a new paradigm that will guide future research”.

It's all about fundamental exploration, without which the surprising discovery of the nanosheet structure would never have been made.

Source: Brookhaven National Laboratory

12 comments
Wolf War
ermm Aluminium?!? cheep and recyclable... I think we need more research/ideas in transportation and manipulation of Hydrogen gas
piperTom
The article refers to hydrogen as an energy source (first paragraph) and as a "solution." Hydrogen COSTS energy. Yes, it can be useful as a way to store or transport energy, but it always consumes energy from some other source.
Kenneth.Spicer
You guys are spoiled by hydrocarbons. Burning hydrocarbons introduces CO2 from millions of years ago. CO2 that is melting the ice caps and sinking NYC. Yes, you have to put energy in H to get energy out. Nothing's for free. Put it in now, or 100 million in the past. BTW, Aluminum is unsuitable, the definition of a catalyst is that it doesn't degrade or corrode in use. Aluminum will corrode, and contaminate the gas rindering it useless.
Graham HomeMaintenance
keep up the research, have you tried using Palladium I recall it acts as a sponge for Hydrogen, as for storage there have been several substances created to hold hydrogen safely.
Michael Mantion
Graham Palladium is almost as rare and expensive as platinum. And yes they have tried it Kenneth? Hydrocarbons are the key to life. Plants, you, me, food, you name it are hydrocarbons. I think you are suggesting that the gas we burn is millions of years old. That is disputable but really insignificant. the ice caps have been melting before the industrial age, NY is not sinking. Even when the ice caps are gone there will be little or no effect on coastal cities. I am not suggesting nothing will change.. Things will change, just as they have done for billions of years. I have no idea what you are suggesting by aluminum corroding and contaminating the gas. No one in the article is suggesting that Hydrogen is magically creating energy. They are suggesting hydrogen is a source of energy just like any fuel source. Our previous president stated hydrogen is the key energy source in the future. I look forward to him being proven correct.
Wolf War
@Kenneth.Spicer I wasn't talking about electrocatalyst http://en.wikipedia.org/wiki/Alchemy_Research
Slowburn
Hydrogen will never be a high-density energy carrier; it will require an entire new infrastructure unless it is converted into hydrocarbon fuels but if we get the energy source that could make hydrogen a viable mass market energy carrier the additional energy input to convert it into methane and then into room temp & pressure liquids is trivial and I will welcome the clean nuclear future.
jerryd
I can make all the H2 I want from waste biomess heating it to 1500F for mostly H2/CO but just what does one do with it that couldn't be better done with the source energy? Let's not forget the eff of the whole H2 cycle. Even in the most eff foolcells are only 50% eff. Higher power ones needing many pumps, etc are lower still. Facts are most eff ICE's are as eff as a foolcell when you take it all into account. Now the eff of making H2 from a high order energy like electricity especially to later make electricity. And how do you store it? H2 is an energy carrier and not a very good one. The only people pushing it are those who are trying to profit off of it. No one who does the numbers is for H2. Though iin some chemical process this could be very helpful, it's not going to ever be a H2 economy unless we want to waste 50% of our energy.
ugachemist
Hydrogen is an energy carrier, not an energy source. That's true. However, it is incredibly appealing in that it could potentially be generated from solar energy. That is where materials like this come in and are so important. Further, it has very little emissions. The product of it's combustion is just water. It is a potentially sustainable fuel, which is something that we currently lack. Of course an infrastructure change will be necessary, but that kind of comes with moving away from a resource that drives an economy. It'll be expensive, for sure. But ultimately, if we are to preserve our lifestyles, we will move toward a hydrogen economy. Research like this catalyzes that process.
waltinseattle
platinoids li palad are rare and they are even more of a trouble to refine singularly. The idea of a CATALYST is, lest some forgot or never knew, the purpose is to minimize the energy required to make hydrogen "fuel." Hell if you want to get technical, oil derivatives also require energy inputs to become our fuels! It is a question of overall and exact math, not just some disparaging remarks about "costs" of obtaning the resource.
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