Skip to comments.Nanosheet catalyst discovered to sustainably split hydrogen from water
Posted on 05/14/2012 7:04:30 AM PDT by Red Badger
Hydrogen gas offers one of the most promising sustainable energy alternatives to limited fossil fuels. But traditional methods of producing pure hydrogen face significant challenges in unlocking its full potential, either by releasing harmful carbon dioxide into the atmosphere or requiring rare and expensive chemical elements such as platinum.
Now, scientists at the U.S. Department of Energys (DOE) Brookhaven National Laboratory have developed a new electrocatalyst that addresses one of these problems by generating hydrogen gas from water cleanly and with much more affordable materials. The novel form of catalytic nickel-molybdenum-nitride described in a paper published online May 8, 2012 in the journal Angewandte Chemie International Edition surprised scientists with its high-performing nanosheet structure, introducing a new model for effective hydrogen catalysis.
We wanted to design an optimal catalyst with high activity and low costs that could generate hydrogen as a high-density, clean energy source, said Brookhaven Lab chemist Kotaro Sasaki, who first conceived the idea for this research. We discovered this exciting compound that actually outperformed our expectations.
Water provides an ideal source of pure hydrogen abundant and free of harmful greenhouse gas byproducts. The electrolysis of water, or splitting water (H2O) into oxygen (O2) and hydrogen (H2), requires external electricity and an efficient catalyst to break chemical bonds while shifting around protons and electrons. To justify the effort, the amount of energy put into the reaction must be as small as possible while still exceeding the minimum required by thermodynamics, a figure associated with what is called overpotential.
For a catalyst to facilitate an efficient reaction, it must combine high durability, high catalytic activity, and high surface area. The strength of an elements bond to hydrogen determines its reaction level too weak, and theres no activity; too strong, and the initial activity poisons the catalyst.
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 James Muckerman, the senior chemist who led the project. The result becomes this well-balanced Goldilocks compound just right.
Unfortunately, the strongest traditional candidate for an electrocatlytic Goldilocks comes with a prohibitive price tag.
Problems with platinum
Platinum is the gold standard for electrocatalysis, combining low overpotential with high activity for the chemical reactions in water-splitting. But with rapidly rising costs already hovering around $50,000 per kilogram platinum and other noble metals discourage widespread investment.
People love platinum, but the limited global supply not only drives up price, but casts doubts on its long-term viability, Muckerman said. There may not be enough of it to support a global hydrogen economy.
In contrast, the principal metals in the new compound developed by the Brookhaven team are both abundant and cheap: $20 per kilogram for nickel and $32 per kilogram for molybdenum. Combined, thats 1000 times less expensive than platinum. But with energy sources, performance is often a more important consideration than price.
Turning nickel into platinum
In this new catalyst, nickel takes the reactive place of platinum, but it lacks a comparable electron density. The scientists needed to identify complementary elements to make nickel a viable substitute, and they introduced metallic molybdenum to enhance its reactivity. While effective, it still couldnt match the performance levels of platinum.
We needed to introduce another element to alter the electronic states of the nickel-molybdenum, and we knew that nitrogen had been used for bulk materials, or objects larger than one micrometer, said research associate Wei-Fu Chen, the papers lead author. But this was difficult for nanoscale materials, with dimensions measuring billionths of a meter.
The scientists expected the applied nitrogen to modify the structure of the nickel-molybdenum, producing discrete, sphere-like nanoparticles. But they discovered something else.
Subjecting the compound to a high-temperature ammonia environment infused the nickel-molybdenum with nitrogen, but it also transformed the particles into unexpected two-dimensional nanosheets. The nanosheet structures offer highly accessible reactive sites consider the surface area difference between bed sheets laid out flat and those crumpled up into balls and therefore more reaction potential.
Using a high-resolution transmission microscope in Brookhaven Labs Condensed Matter Physics and Materials Science Department, as well as x-ray probes at the National Synchrotron Light Source, the scientists determined the materials 2D structure and probed its local electronic configurations.
Despite the fact that metal nitrides have been extensively used, this is the first example of one forming a nanosheet, Chen said. Nitrogen 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 new catalyst performs nearly as well as platinum, achieving electrocatalytic activity and stability unmatched by any other non-noble metal compounds. The production process is both simple and scalable, Muckerman said, making nickel-molybdenum-nitride appropriate for wide industrial applications.
While this catalyst does not represent a complete solution to the challenge of creating affordable hydrogen gas, it does offer a major reduction in the cost of essential equipment. The team emphasized that the breakthrough emerged through fundamental exploration, which allowed for the surprising discovery of the nanosheet structure.
Brookhaven Lab has a very active fuel cell and electrocatalysis group, Muckerman said. We needed to figure out fundamental approaches that could potentially be game-changing, and thats the spirit in which were doing this work. Its about coming up with a new paradigm that will guide future research.
Additional collaborators on this research were: Anatoly Frenkel of Yeshiva University, Nebojsa Marinkovic of the University of Delaware, and Chao Ma, Yimei Zhu and Radoslav Adzic of Brookhaven Lab.
More information: Scientific Paper: Hydrogen-Evolution Catalysts Based on Non-Nobel Metal NickelMolybdenum Nitride Nanosheets
Well soap, at least.
Like garlic to a vampire........or is that werewolves?....I forget..............
Mr. Badger, this seems to relate to the other article you posted a month ago.
Hybrid copper-gold nanoparticles convert CO2 (To Hydrocarbons!)
I find the site that both articles link to rather interesting. There was a show on PBS about 16 years ago about the speed of technological change. One of the statements made in the show was that if you were to take a man of “today” and project him 25 years in the future, they would think the world of that future worked on magic.
Time has proven that to be absolutely true. We have ten years to go, yet look what we have done since then. In 1996, few people had heard of the internet. Few people had cell phones and even home computers were essentially used for Microsoft works or lame games. And GPS for the masses, and smart phones, and on and on. A lot has changed. A lot more (exponentially speaking) will in the next ten years.
Well yeah - that was kind of the joke.
I wouldn’t mind living in a cave as long as it had central heat and AC with satellite and Internet................
Stopped reading after the first sentence. Virtually all of the combustible Hydrogen on the planet is tied up in the biosphere, laying on the ocean floor, or conveniently bound to long chains of Carbon and buried in the ground.
—Hydrogen and oxygen recombine to make water vapor, which is a hundred times more powerful of a greenhouse gas than CO2, ergo it must be stopped...—
The water vapor should be easily condensed and dumped right back into the tank. Imagine car crashes that involve a leaking fuel tank, which means the passengers get wet...
—China has all the molybdenum.—
Obviously they’ve never heard of The Brothers O’toole and the town of “Mollybedamned”.
does it get more out than is put in?
Water provides an ideal source of pure hydrogen abundant and free of harmful greenhouse gas byproducts.
Under AGW theory, water vapor is a more powerful greenhouse gas than CO2.
The PC that was on the desk was an IBM XT 286 and was used primarily for writing business letters and accessing the mainframe:
We had a Coleco Adam computer at home that was primarily a game machine:
CD still stood for 'Certificate of Deposit' and VHS was battling Beta for dominance in the market.
Both the Challenger and Chernobyl blew up and Michael Jackson was still black................
No, the amount of hydrogen remains the same............
so... the energy output is equal to the energy input?
I sold electronics from 1996 through 1982. I owned Beta and Laserdisk. ;)
I also have an IBM XT that I save as an “antique”. It has that nice green screen, 8” floppy drive and Microsoft Works. I also sold Atari 400’s and 800’s back in the day.
I also remember the first version of Encarta, which was made utterly obsolete by the web. The part I remember the most is the explanation of how a jet engine works. It actually included an animation of an engine doing what it does with clear explanation of the functionality of the components.
That was the moment I realized that Public Schools would die. A picture is worth a thousand words, and a single piece of software that is able to explain better than any teacher, and allow the student to partially or fully rewind to review if there was any confusion. And now we have things like this: Khanacademy.org
Give it all another ten years.
Ask the next plant you see how harmful carbon dioxide is.
There are losses of course, but the extraction of hydrogen is cheaper than using platinum....
All those inventions were initially funded for military purposes. If we continue to cut military spending to fund welfare spending as Barky is doing then leaps in technology will slow to a snail striddle. The reason America leads in technology is because we fund a big military. The wealth of a nation is correlated with how much military investment was made 30 to 40 years ago.
Yes it does sound almost like like a perpetual motion - water in, water out, and the car moves. I can’t believe anything would work that way.
ON the other hand, if it DID work, I can see a potential application in ammo - the human body being about 70% water... Might make for a heck of wound if you have to take down zombies or goblins.
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