The novel form of catalytic nickel-molybdenum-nitride is described in a paper published online May 8, 2012 in the journal Angewandte Chemie, International Edition.

Hydrogen gas offers one of the most promising sustainable fuel alternatives. But traditional methods of producing pure hydrogen face significant challenges in unlocking its full potential, either by releasing carbon dioxide when its sourced from natural gas or requiring rare and expensive chemical elements such as platinum hwne sourced from water by electrolysis.

The new electro catalyst surprised the scientists with its high-performing nanosheet structure, introducing a new model for effective hydrogen catalysis.

Brookhaven's Nickel Molybdenum Nitride Catalyst for Splitting Water

Brookhaven Lab chemist Kotaro Sasaki, who first conceived the idea for this research explains, “We wanted to design an optimal catalyst with high activity and low costs that could generate hydrogen as a high-density, clean energy source. We discovered this exciting compound that actually outperformed our expectations.”

Background – Water provides an ideal source of pure hydrogen its abundant and free of harmful CO2 gas byproducts. The electrolysis of water, or splitting water (H2O) into oxygen (O2) and hydrogen (H2), requires electric current and an efficient catalyst to break chemical bonds while shifting around the 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 element’s bond to hydrogen determines its reaction level, if its too weak, and there’s no activity; too strong, and the initial activity poisons the catalyst.  Unfortunately, the strongest traditional candidate for electro catalytic activity, platinum, comes with a prohibitive price tag.

Platinum is the top material for electro catalysis, combining low overpotential with high activity for the chemical reactions during water-splitting. But with rapidly rising costs, already hovering around $50,000 per kilogram, platinum and other noble metals discourage widespread use
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James Muckerman, the senior chemist who led the project takes up the explanation with, “People love platinum, but the limited global supply not only drives up price, but casts doubts on its long-term viability. There may not be enough of it to support a global hydrogen economy.”
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 – that’s 1000 times less expensive than platinum. But with energy sources, performance is often a more important consideration than price.

“We needed to create high, stable activity by combining one non-noble element that binds hydrogen too weakly with another that binds too strongly. The result becomes this well-balanced Goldilocks compound – just right.”  That simple explanation makes clear what the team managed to do.

In the 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 couldn’t match the performance levels of platinum.

Now research associate Wei-Fu Chen, the paper’s lead author takes up the explanation, “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. 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 and more reaction potential.

Using a high-resolution transmission microscope in Brookhaven Lab’s Condensed Matter Physics and Materials Science Department, as well as x-ray probes at the National Synchrotron Light Source, the scientists determined the material’s 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 Brookhaven catalyst performs nearly as well as platinum, achieving electro catalytic 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.

This is really good news.  Currently most industrial hydrogen is sourced from natural gas so coming up with a competitive water based source is quite useful.  Even as natural gas is at a very low price, the hydrogen needed could grow if the price could be driven furthr down.

For many experimenters aluminum has been the electro catalyst of choice.  Getting the new Brookhaven material out into the hands of the thousands of experimenters making Browns Gas.  The new material could be a step into much more and more efficient hydrogen use.

Deli Wang, professor in the Department of Electrical and Computer Engineering at the UC San Diego Jacobs School of Engineering quoted in the University press release said, “This is a clean way to generate clean fuel.”  The study paper is at the journal Nanoscale.

The nanowires look quite like trees in the photo, becoming a forest.  The team’s press release offers Wang’s explanation – The trees’ vertical structure and branches are keys to capturing the maximum amount of solar energy because the vertical structure of trees grabs and adsorbs light while flat surfaces simply reflect it.  It’s similar to retinal photoreceptor cells in the human eye. There’s a clue in images of Earth from space, light reflects off of flat surfaces such as the ocean or deserts, while forests appear darker.

Nanotrees for Generating Hydrogen. Click image for the largest view. Image credit, Wang Research Group, UC San Diego Jacobs School of Engineering

That intuitive grasp of the opportunity to build a more three-dimensional structure suggested a “3D branched nanowire array”.  Inside the forest the process called photoelectrochemical water splitting produces hydrogen gas.  This process uses sunlight energy with no greenhouse gas byproduct. By comparison, the current conventional way of producing hydrogen relies on generated electricity or high temperature reforming using fuel sources

Ke Sun, a PhD student in electrical engineering who led the project said, “Hydrogen is considered to be clean fuel compared to fossil fuel because there is no carbon emission, but the hydrogen currently used is not generated cleanly.”  Clearly the team has a “clean” motive at least as far as most likely the funding and perhaps further research.  That’s fine if they get to a low cost hydrogen generation system.

On the technical details Wang’s team has developed a way to harvest more sunlight using the vertical nanotree structure that is said to produce more hydrogen fuel efficiently compared to planar counterparts.

Along with the vertical structure efficiency gains, the structure maximizes hydrogen gas output.  Sun explains for example, on the flat wide surface of a pot of boiling water, bubbles must become large to come to the surface. In the nanotree structure, very small gas bubbles of hydrogen can be extracted much faster.

Sun said, “Moreover, with this structure we have enhanced by at least 400,000 times the surface area for chemical reactions.”

But aside from the commentary, neither the press release nor the study abstract are detailing how much hydrogen is produced per surface area.  No information is discussed on the costs per area.  There isn’t any data on the operation.

Still, the concept is a striking and effective innovation on the quality of sunlight and its harvest.  If the numbers on building modules are reasonable and operating costs low this is an idea that suggests a little sunlit area could go a long way for making hydrogen fuel.

For the long-term Wang’s team is aiming for artificial photosynthesis.  Artificial photosynthesis is a fine idea, but generating hydrogen is a mighty fine idea on its own that’s deserves a closer look and perhaps development.

Wang’s team hopes to mimic photosynthesis to also capture CO2 from the atmosphere, reducing carbon emissions, and convert it into hydrocarbon fuel.

Sun said, “We are trying to mimic what the plant does to convert sunlight to energy. We are hoping in the near future our ‘nanotree’ structure can eventually be part of an efficient device that functions like a real tree for photosynthesis.”

There’s quite a bit of competition in the artificial photosynthesis effort.  Everyone remains bedeviled in capturing the CO2.  The recombining of the carbon and hydrogen remains economically elusive as well.

The team is upfront with their plans. Its also being said the team is studying alternatives to zinc oxide, which absorbs the sun’s ultraviolet light, but has stability issues that affect the lifetime usage of the nanotree structure.

This looks like another in a series of sunlight to hydrogen processes of which there are many.  It’s noticeable now that few ever note the actual productivity per area.  This should be casting a long shadow.  CO2 is a very small part of the atmosphere; its harvest at scale is going to be a major hurdle.  Competition with plants for getting to carbon molecules that are useful or easily reformed to fuel products is another substantial hurdle.

The test should be, can the research ideas get competitive to the common processes to free hydrogen?  Electrolysis isn’t cheap nor is steam reforming.  There is a huge market for hydrogen now.  Should a market scale low cost hydrogen fuel cell break out, a lot of researchers and funding sources are going to wonder why they chased artificial photosynthesis when they may well have a block busting revolution on the self.

This concept looks like a great idea. Let’s hope the politically correct atmosphere doesn’t derail a good idea off onto a shelf somewhere.

Quote, “When lots of these single-molecule catalysts were dumped into acidic water and even seawater, they generated hydrogen for several days without letup.”  Your humble writer is contacting the press release author and asking that the statement be confirmed or corrected.  If the statement is factually correct, then the UCB chemists have cracked open a major opportunity to get a source of free hydrogen without energy input – creating a true threshold for an energy production revolution.  Lets hope the report is correct.

*Update Feb 15, 2012:

Hi, Brian. There is, of course, an energy input – electricity. They are trying to generate that electricity from solar. I should have spelled that out and not assumed it to be a given.–Bob

We’ll ask about efficiency as they make progress.*

Meanwhile, getting to that point is research led by Christopher Chang, associate professor of chemistry and Howard Hughes Medical Institute Investigator at UCB.  The study paper was published last week the journal Science, showing how to construct a catalyst composed only of edges and demonstrate that it can catalyze the production of hydrogen from water as readily as the edges and defects in regular catalysts.

Chang said, “This is a conceptual advance in the way we think about generating hydrogen, a clean burning fuel, from water, a sustainable source. Our new catalyst is just first generation, but the research gives us and the community a path forward to thinking about how to increase the density of functional active sites so that molecules and materials can be more effective catalysts.”

Chang and the UCB research team are working with a common catalyst, molybdenite, which is less expensive than platinum.  Molybdenite is composed of molybdenum and sulfur (MoS2) and is getting increasing interest as a fuel cell catalyst.  When built up to an optimum shape the material catalyzes reactions like the splitting of water into hydrogen and oxygen only at the edges, where triangles of molybdenum and two sulfur atoms stick out like pennants to react with the reactants.

Change explains, “These edge sites look like little MoS2 triangles, and the triangular area does the business.”

Customarily catalysts are usually metals that speed up chemical reactions.  They’re used across the chemical industry, petroleum industry and as close to each of us as the catalytic converter in automobile exhaust.  The big goal in catalytic conversion is the fuel cell, to extract the energy of hydrogen into electricity.

The UCB team is seeking to find ways to expose as much as possible of the catalyst material surface where the chemistry can be assisted in the reaction.  The engineering then would greatly reduce the amount of catalyst needed to get the reaction accomplished.

Chang and his colleagues created a small carbon framework using complex organic synthesis techniques to hold the MoS2 triangle so that “every molecule has a discrete edge site that is a catalytically active unit.”  Those are what are thought to have been dropped into to the acidic and sea water.

The future goal is maximizing the number of catalytic sites for a given volume and boosting ultimate efficiency.  Chang hopes to assemble billions of these molecules on a thin, ridged wafer.

Looking ahead Chang said, “There are many other types of materials out there for which people might want to generate edge-site fragments rather than use a bulk material with just a few edge or defect sites. With hydrogen being touted as a clean burning fuel that generates no CO2, creating cheaper and better catalysts has become a big and important field now. The main push is toward more earth-abundant materials than the rare metals like platinum.”

The UCB team members working with Chang are Jeffrey R. Long, UC Berkeley professor of chemistry and faculty scientist at Lawrence Berkeley National Laboratory, professor of chemistry Marcin Majda, and post-doctoral fellows Hemamala I. Karunadasa, Elizabeth Montalvo and Yujie Sun.

It will be quite an interesting development if the UCB team has established threshold of producing hydrogen without an energy input.  One would expect intense efforts to get practical systems at scale as soon as possible at economical pricing.  A low cost, long lasting catalyst making cheap hydrogen would be a sea change in energy economics.

The research abstract hints and the press release is quite bold.  One sure hopes its not an error or misinterpretation.

Hydrates are a water ice and usually a natural gas compound that have been explored by researchers as a source of alternative fuel or storage medium for CO2.  The PNNL researchers note at first discovery the hydrogen storage value approaches the goal of a Department of Energy standard and could make hydrogen hydrates practical and affordable for storage.

Using computer analysis of the ice and gas compound reveals key details of its structure and researchers have accurately quantified the molecular-scale interactions between the gases of either hydrogen or methane, also known as natural gas – and the water molecules that the form cages around them.

The research team’s results from the Department of Energy’s Pacific Northwest National Laboratory were published in Chemical Physics Letters online December 22, 2011.

While hydrogen is the most interesting use of hydrates, PNNL chemist Sotiris Xantheas the lead author said, the results could also provide insight into the process of replacing methane with carbon dioxide in the naturally abundant “water-based reservoirs.”

Here’s the marvel revealed in the research as put by Xantheas, “Current thinking is that you need large amounts of energy to push the methane out, which destroys the scaffold in the process. But the computer modeling shows that there is an alternative low energy pathway. All you need to do is break a single hydrogen bond between water molecules forming the cage – the methane comes out, and then the hydrate reseals itself.”  This revelation has major implications on natural gas recovery.

Previously Xantheas and the colleagues used computer algorithms and models to examine the water-based, ice-like scaffold that holds the gas. Water molecules form individual cages made with 20 or 24 molecules. Multiple cages join together in large lattices. But those scaffolds were empty in the earlier analysis.

To find out how fuels can be accommodated inside the water cages, Xantheas and colleague Soohaeng Yoo Willow built computer models of the cages with either hydrogen gas – in which two hydrogen atoms are bound together – or methane gas, a small molecule made with one carbon and four hydrogen atoms.

In the hydrogen hydrates, the idea that could potentially be used as materials for hydrogen fuel storage, a small hollow cage made from 20 water molecules could hold up to a maximum of five hydrogen molecules and a larger cage made from 24 water molecules could hold up to seven.

The maximum storage capacity equates to about 10 weight-percent, or the percentage of hydrogen by mass in the chunks of ice.

However packing hydrogen in that tight puts undue strain on the system.  But it nearly doubles the DOE’s goal for hydrogen storage above a 5.5 weight-percent.

Now the story gets intuitive, innovative and just clever.  Experimentally, hydrogen storage researchers typically measure much less storage capacities. The computer model showed them why: The hydrogen molecules tended to leak out of the cages, reducing the amount of hydrogen that could be stored.

The PNNL team found that adding a methane molecule to the larger cages in the pure hydrogen hydrate prevented the hydrogen gas from leaking out. The computer model showed the researchers that they could store the hydrogen at high pressure and practical temperatures, and release it by reducing the pressure, which melts it.

Understanding how the gas interacts and moves through the cages can help chemists or engineers store gas and remove it at will.

Willow and Xantheas’ computer simulations showed that hydrogen molecules could migrate through the cages by passing between the figurative bars of the water cages. However there’s a problem to work out, the cages also had gates: Sometimes a low-energy bond between two water molecules broke, causing a water molecule to swing open and let the hydrogen molecule drift out. The “gate” closed right after the molecule passed through to reform the lattice.

With methane hydrates, some fuel producers want to remove the gas safely to use it.  So, Willow and Xantheas tested how methane could migrate through the cages.

The water cages are only big enough to comfortably hold one methane molecule, so the chemists stuffed two methane molecules inside and watched what happened. Quickly, one of the water molecules forming the cage swung open like a gate, allowing one methane molecule to escape. The gate then slammed shut as the remaining molecule scooted into the middle of the cage.

Xantheas explains, “This process is important because it can happen with natural gas. It shows how methane can move in the natural world. We hope this analysis will help with the technical issues that need to be addressed with gas hydrate research and development.”

The team’s work is still all in the computer, but the insight should allow a broad spectrum of researchers a blueprint for experimentation and the beginning steps of processes and engineering.  The best news is the storage rate is very high and the temperatures are in an easy to access zone with common refrigeration and low energy requirements to do the warm up.  The engineering challenge to today is substantial, but some very good minds are going to light up with this news.

Researchers at the U.S. Department of Energy’s (DOE) Argonne National Laboratory have come up with an extraordinarily efficient two-step process that electrolyzes, or separates, hydrogen atoms from water molecules before recombining them to make molecular hydrogen (H2), which can be used in any number of applications from fuels to industrial production.  The paper is now published in Science.

Argonne Platinum Catalyst Hydrogen Production Activity Graphic. Click image for more info.

Cheaper and more efficient production of hydrogen gas has long been a target of scientists and engineers, primarily due to the gas creation requiring a great deal of energy. The DOE offers that approximately 2% of all electric power generated in the United States is dedicated to the production of molecular hydrogen, making a strong motivator for scientists and engineers searching to find any way to cut electrical use.

Nenad Markovic, the Argonne senior chemist who led the research said, “People understand that once you have hydrogen you can extract a lot of energy from it, but they don’t realize just how hard it is to generate that hydrogen in the first place.”

For now a great deal of hydrogen is created by reforming natural gas at high temperatures, a process that releases those annoying carbon-dioxide emissions.  Makovic takes the point on, “Water electrolyzers are by far the cleanest way of producing hydrogen. The method we’ve devised combines the capabilities of two of the best materials known for water-based electrolysis.”

Many of the highly efficient water-based electrolysis processes rely on metal catalysts like platinum to adsorb and recombine reactive hydrogen intermediates into stable molecular hydrogen. Markovic’s research focuses on the absorption step that involves improving the efficiency by which an incoming water molecule would disassociate into its fundamental components. To do this, Markovic and his colleagues added clusters of a metallic complex known as nickel-hydroxide – Ni(OH)2.  When the nickel-hydroxide is attached to a platinum framework the clusters tore apart the water molecules, allowing for the freed hydrogen to be catalyzed by the platinum to H2 gas.

The process involved growing conductive ultra-thin Ni(OH)2 clusters (height 0.7 nm, width 8 to 10 nm) on both pristine Pt single-crystal surfaces and Pt surfaces modified by two-dimensional (2D) Pt ad-islands [Pt-islands/Pt(111)].

“One of the most important points of this experiment is that we’re combining two materials with very different benefits. The advantage of using both oxides and metals in conjunction dramatically improves the catalytic efficiency of the whole system,” said Markovic.

The source technology, according to Argonne materials scientist George Crabtree, who helped to initiate the establishment of Argonne’s energy conversion program, is the researchers’ ability to work successfully on what are known as “single-crystal” systems – defect-free materials that allow scientists to accurately predict how certain materials will behave at the atomic level.

Crabtree comes close to exploring the efficiency gain with, “We have not only increased catalytic activity by a factor of 10, but also now understand how each part of the system works. By scaling up from the single crystal to a real-world catalyst, this work illustrates how fundamental understanding leads quickly to innovative new technologies.”

At a given production rate an increase by a factor of 10 suggests a 90% reduction in precious platinum investment for the catalyst.  But the neither the study abstract or the press release is clear on that.  It may also have an impact on the electrical draw, but that matter also isn’t covered.

However the team is calculating getting to a factor of 10 the point is clear, they have worked up a catalyst sandwich that works far better than standard precious metal electrolysis.  Now if the catalyst can be made at commercial scale they’ll really have something – there’s a huge demand for hydrogen now, and cheaper hydrogen gas will only make the market larger.

The N part or nitrogen is great stuff, it makes up about 80% of the atmosphere and its highly non-reactive and stabile tendency is a very good thing.  If oxygen and nitrogen were reversed in atmospheric proportion the oxidation rates and combustion potential would make life as we know it impractical.  It a very good thing there is so much around.  But for making things like NH3 that stability and non-reactive nature is a problem.

Then the 100+ year old Haber-Bosch Process (HBP) is a hot and high pressure process.  It takes a lot of energy and usually uses an energy source like natural gas to get the hydrogen for building the molecules.  How HBP works, though, hasn’t been explained so far.

But HBP works and works well, reliably and it’s a well-entrenched technology with a vast industrial base.  It’s not going to change without powerful incentives.

How HBP works at the catalysts surface has been something of a mystery until now. Scientists have had little understanding of how it actually works.  Now a team of chemists, led by Patrick Holland of the University of Rochester, has new insight into how the ammonia is formed. Their findings have been published in the latest issue of Science.

Holland calls nitrogen molecules “challenging.” They’re abundant so they’re desirable for research and manufacturing, but their strong triple bonds are difficult to break, making them highly unreactive. For the last century, HBP has made use of an iron catalyst at extremely high pressures and high temperatures to break those bonds and produce ammonia, one drop at a time.

Holland said, “The Haber-Bosch process is efficient, but it is hard to understand because the reaction occurs only on a solid catalyst, which is difficult to study directly. That’s why we attempted to break the nitrogen using soluble forms of iron.”

Holland’s team, which includes Meghan Rodriguez and William Brennessel at the University of Rochester and Eckhard Bill of the Max Planck Institute for Bioinorganic Chemistry in Germany have succeeded in mimicking the process in solution.

They discovered that an iron complex combined with potassium was capable of breaking the strong bonds between the nitrogen atoms and forming a complex with an Fe3N2 core, which indicates that three iron (Fe) atoms work together in order to break the N-N bonds. The new complex then reacts with hydrogen (H2) and acid to form ammonia (NH3) – something that had never been done before by iron in solution.

Using the atmosphere’s N2 molecule cracked apart makes the NH3 build possible.  Knowing the crack needs three iron atoms working together is going to have implications for process designers.   Anything to cut costs such as lower operating pressures and or temperatures is going to help.

Holland makes clear that his new process isn’t going to be directly applicable because the team’s catalyst is much more expensive.  But Holland says it is possible that his team’s research could eventually help in coming up with a better catalyst for the HBP – one that would allow ammonia to be produced at lower temperatures and pressures.

Like lots of other research another point came up.  When the team’s iron-potassium complex breaks apart the nitrogen molecules, negatively charged nitrogen ions – called nitrides are formed. Holland says the nitrides formed in solution could be useful in making pharmaceuticals and other products.

Now the work needs done of confirming the iron potassium catalyst truly matches the strictly iron activity.  If that works, like it should, then new catalyst designs would become worthy ideas. That’s when the opportunities for lower energy inputs needed for the temperature and pressures might appear.

This is good basic research.  Now, subject to confirmation, the activity of making the N2 into to a simple N can be visualized.  Keep in mind the new catalyst also does the re combine with the hydrogen as well.

Catalyst research on a hundred year old success is getting NH3 a bit closer to getting some more market traction.

Two catalysts are needed for such a reaction, one that liberates the hydrogen atoms, and another for the oxygen atoms, but the oxygen reaction has been the limiting factor in such systems.

A team of researchers at MIT has found one of the most effective catalysts ever discovered for splitting oxygen atoms out from water molecules.  The new catalyst liberates oxygen at more than 10 times the rate of the best previously known catalyst of its type.  How much current is needed or the efficiency isn’t however noted.  Meanwhile, the numbers are astonishing and the catalyst has no precious metals.

The MIT team says the new compound, composed of cobalt, iron and oxygen with other metals, splits oxygen from water (called the Oxygen Evolution Reaction, or OER) at a rate at least an order of magnitude higher than the compound currently considered the gold standard for such reactions. The compound’s high level of activity was predicted from the team’s systematic experimental study that looked at the catalytic activity of 10 known compounds.

Proposed OER Mechanism on Perovskite from MIT. Click image for more info.

The team’s results were published in Science on Oct. 28, 2011.

The research turned up other interesting clues.  The MIT team found that reactivity depended on a specific characteristic: the configuration of the outermost electron of transition metal ions. They were able to use this information to predict the high reactivity of the new compound, which they then confirmed in lab tests.  That aspect shows there may well be other catalyst compounds to discover.

Shao-Horn, the Gail E. Kendall (1978) Associate Professor of Mechanical Engineering and Materials Science and Engineering said, “We not only identified a fundamental principle that governs the OER activity of different compounds, but also we actually found this new compound based on that principle.”

MIT’s Daniel Nocera, is focused on similar catalysts that can operate in a so-called “artificial leaf”, at low cost in ordinary water. But such reactions can occur with higher efficiency in alkaline solutions, which are required for the best previously known catalyst, iridium oxide, as well as for this new compound.

Shao-Horn and her collaborators including materials science and engineering graduate student Jin Suntivich, mechanical engineering graduate student Kevin J. May are now working with Nocera, integrating their catalyst with his artificial leaf to produce a self-contained system to generate hydrogen and oxygen when placed in an alkaline solution.

They will also be exploring different configurations of the catalyst material to better understand the mechanisms involved. Their initial tests used a powder form of the catalyst; now they plan to try thin films to better understand the reactions.

Shao-Horn says “It’s our belief that there may be others with even higher activity.”  The team plans to continue searching for even more efficient catalyst materials.  The new catalyst may be a leader for along time though, as the top choice was made from a new understanding to the basic operation of taking off the oxygen atom.

Splitting water to acquire free hydrogen is a demanding job.  The water molecule has good bonds needing a lot of effort to break apart.  Its one thing to just carve off a hydrogen atom leaving the HO and quite another to get all the way to fully freed hydrogen and oxygen.

Without a discussion of the energy involved a comparison with the practicing process in use now isn’t possible.  That may be an oversight or simply not having good data or the catalyst demands inordinate power.  It’s the information everyone is waiting to see.

MIT has the raw speed catalyst to spilt water now – which is no small feat.  Lets keep an eye out for the power demands and hope the efficiency has a noteworthy improvement as well.

Nocera’s artificial leaf is a silicon solar cell with different catalytic materials bonded onto its two sides that need no external wires or control circuits to operate. Placed in a container of water and exposed to sunlight, it quickly begins to generate streams of bubbles: oxygen bubbles from one side and hydrogen bubbles from the other. If placed in a container that has a barrier to separate the two sides, the two streams of bubbles can be collected and stored, and used later to deliver power: for example, by feeding them into a fuel cell that combines them once again into water while delivering an electric current.

Nocera's Synthetic Leaf. Click image for more info.

The property of releasing the hydrogen and the oxygen on different sides seizes attention.  Production of hydrogen without the oxygen allows many more useful paths for the hydrogen as well as avoiding a step to separate the two.  Most production splits the water and produces the elements combined, a highly volatile mixture called Brown’s gas.

The artificial leaf is a thin sheet of semiconducting silicon – the material most solar cells are made of – which turns the energy of sunlight into a flow of wireless electricity within the sheet. Bound onto the silicon is a layer of a cobalt-based catalyst, which releases oxygen, a material whose potential for generating fuel from sunlight was discovered by Nocera and his co-authors in 2008. The other side of the silicon sheet is coated with a layer of a nickel-molybdenum-zinc alloy, which releases hydrogen from the water molecules.

Nocera says, “I think there’s going to be real opportunities for this idea. You can’t get more portable – you don’t need wires, it’s lightweight, and it doesn’t require much in the way of additional equipment, other than a way of catching and storing the gases that bubble off. You just drop it in a glass of water, and it starts splitting it.”

At this point the technology sounds superb.  Not fully satisfied, Nocera suggests one possible further development: tiny particles made of these materials that can split water molecules when placed in sunlight — making them more like photosynthetic algae than leaves. The advantage of that, he says, is that the small particles would have much more surface area exposed to sunlight and the water, allowing them to harness the sun’s energy more efficiently.  Except engineering a system to separate and collect the two gases would be more complicated.

For now the new device is not yet ready for commercial production, since systems to collect, store and use the gases remain to be developed. “It’s a step,” Nocera says. “It’s heading in the right direction.”

Nocera’s vision is a future in which individual homes could be equipped with solar-collection systems based on this principle: Panels on the roof could use sunlight to produce hydrogen and oxygen that would be stored in tanks, and then fed to a fuel cell whenever electricity is needed. Such systems, Nocera hopes, could be made simple and inexpensive enough so that they could be widely adopted throughout the world, including many areas that do not presently have access to reliable sources of electricity.  Enough roof area and one might power personal transport or offer hydrogen and oxygen for sale.

Presently the leaf can redirect about 2.5 percent of the energy of sunlight into hydrogen production in its wireless form; a variation using wires to connect the catalysts to the solar cell rather than bonding them together has attained 4.7 percent efficiency.  The MIT article hasn’t addressed the costs directly saying Nocera’s ongoing research with the artificial leaf is directed toward pushing down the production costs as well as looking at ways of improving the system’s efficiency.

Without doubt, this technology path has potential.  A solid-state cell with a lifespan measured in decades or more would have a very long amortization.  The attraction is the hydrogen release without the oxygen.  There are lots of technologies using electrolysis for splitting water, but clean hydrogen for storage is a great simplification worth quite a lot in capital cost and operation expense.

Nocera has started Sun Catalytix to commercialize his solar-energy inventions with paper co-author Steven Reece PhD ’07 working there.   Lets hope the firm can get something truly low cost out for others to begin innovating with.  Cheap hydrogen would be a great spark for new innovations.

Kappe says with no overstating here, “This system could produce hydrogen anyplace that there is wastewater near seawater. It uses no grid electricity and is completely carbon neutral. It is an inexhaustible source of energy.”

Logan with postdoctoral fellow Younggy Kim use microbial electrolysis cells that produce hydrogen for the basis of the development whereas previously to produce hydrogen, the fuel cells required some electrical input.

The study results were published in the Sept. 19 issue of the Proceedings of the National Academy of Sciences. The team concludes the abstract by saying, “These results show that pure hydrogen gas can efficiently be produced from virtually limitless supplies of seawater and river water and biodegradable organic matter.”

Bacterial Hydrolysis Cell With RED Stack

The key to these microbial electrolysis cells is reverse-electrodialysis or RED that extracts energy from the ionic differences between salt water and fresh water. A RED stack consists of alternating ion exchange membranes – positive and negative – with each RED contributing additively to the electrical output.

For RED technology to hydrolyze water – splitting it into hydrogen and oxygen – requires 1.8 volts, which would in practice require about 25 pairs of membranes and increase pumping resistance.  But combining RED technology with exoelectrogenic bacteria – the bacteria that consume organic material and produce an electric current – reduced the number of RED stacks to only five membrane pairs.

Logan points up the problem, “People have proposed making electricity out of RED stacks. But you need so many membrane pairs and are trying to drive an unfavorable reaction.”

The team’s cells were between 58 and 64 percent efficient and produced between 0.8 to 1.6 cubic meters of hydrogen for every cubic meter of liquid through the cell each day. The researchers estimated that only about 1 percent of the energy produced in the cell was needed to pump water through the system.

Previous work with microbial electrolysis cells showed that they could, by themselves, produce about 0.3 volts of electricity, but not the 0.414 volts needed to generate hydrogen in those fuel cells. Adding less than 0.2 volts of outside electricity released the hydrogen. Now, by incorporating 11 membranes – five membrane pairs that produce about 0.5 volts – the cells produce hydrogen.

Logan says in overlooking the modern situation, “The added voltage that we need is a lot less than the 1.8 volts necessary to hydrolyze water. Biodegradable liquids and cellulose waste are abundant and with no energy in and hydrogen out we can get rid of wastewater and by-products. This could be an inexhaustible source of energy.”

That’s a pretty broad statement and relies on a controlled waste steam.  But the cost of energy from current sources suggests the idea may have the ability t break out into marketing.

The other main question is the cost of production units and operating expense.  That could be the make or break of this kind of idea.  The team’s research used platinum as a catalyst on the cathode, but subsequent experimentation showed that a non-precious metal catalyst, molybdenum sulfide, had 51 percent energy efficiency.  That’s giving up on the order of 10% – not such a huge difference.

Lets encourage the team to keep going.  The resource for the bacteria feeding and the salted side of the water are nearly free and available nearly everywhere.  This just might work – and may even be automated at low cost.  Paired to a combustor for heat or a low cost fuel cell for electrical energy  -  Free Energy just might be a fully credible idea.

Hydrogen Generating Catalyst Based on Hydrogenase. Click image for more info.

A common microbe stores energy in the bonds of hydrogen gas with the help of a protein called a hydrogenase.  Plants use photosynthesis to store the sun’s energy in chemical bonds, which other organisms use when they eat the plants as food.  The PNL researchers wanted to pull out the active portion of the biological hydrogenase and redesign it into a catalyst with a stable chemical backbone.

The PNL researchers report in the August 12 issue of the journal Science, the synthesized catalyst clocks in at 100,000 molecules of hydrogen gas every second.  That step is just one of a series of reactions to split water and make dihydrogen (H2) gas, but the researchers say the early result shows they can learn from nature how to control those reactions to make durable synthetic catalysts for energy storage.

Currently, the materials that spur reactions along called catalysts rely on expensive metals such as platinum.  Coauthor Morris Bullock starts the explanation with, “This nickel-based catalyst is really very fast. It’s about a hundred times faster than the previous catalyst record holder. And from nature, we knew it could be done with abundant and inexpensive nickel or iron.”

In the study the researchers looked at only one small part of splitting water into hydrogen gas.  Of the many steps, there’s one at the end when the catalyst has a hold on two hydrogen atoms that it has stolen from water and then snaps the two together making the H2 gas.

The catalyst does this by completely dismantling some hydrogen atoms from a source such as water and moving the pieces around. Due to the simplicity of hydrogen atoms, those pieces are positively charged protons and negatively charged electrons. The catalyst arranges those pieces into just the right position so they can be put together correctly. “Two protons plus two electrons equals one molecule of hydrogen gas,” says Bullock.

“We looked at the hydrogenase and asked what is the important part of this?” said Bullock. “The hydrogenase moves the protons around in what we call a proton relay. Where the protons go, the electrons will follow.”

Based on the hydrogenase’s proton relay, the experimental catalyst contained regions called “pendant amines” that dangled off the main structure and attracted protons.  A pendant amine moves a proton into position on the edge of the catalyst, while a nickel atom in the middle of the catalyst offers a hydrogen atom with an extra electron (that’s a proton and two electrons for those keeping track).

The pendant amine’s proton is positive, while the nickel atom is holding on to a negatively charged hydrogen. Positioned close to each other, the opposites attract and the conglomerate solidifies into a molecule, forming the dihydrogen gas.

With that plan in mind, the team built potential catalysts and tested them. On their first try, they put a bunch of pendant amines around the nickel center, thinking more would be better. Testing their catalyst, they found it didn’t work very fast. An analysis of how the catalyst was moving protons and electrons around suggested too many pendant amines got in the way of the perfect reaction. An overabundance of protons made for a sticky catalyst, which pinched it and slowed down the hydrogen-gas-forming reaction.

Then the team trimmed a few pendant amines off their catalyst, leaving only enough to make the protons stand out, ready to accept a negatively charged hydrogen atom.  The team found the newly trimmed catalyst performed much better than anticipated. At first they used conditions in which no water was present and the catalyst could create hydrogen gas at a rate of about 33,000 molecules per second. That’s much faster than their natural inspiration of hydrogenase, which clocks in at around 10,000 per second.

Most real-life applications will have water around, so the team added water to the reaction to see how it would perform. The catalyst ran three times as fast, creating more than 106,000 hydrogen molecules every second.

There remains an issue.  The new catalyst isn’t very efficient. The catalyst runs on electricity – because it needs the electrons to pack into the chemical bonds – but it requires more electricity than practical, a characteristic called overpotential exists.  While the overpotential is in place with a platinum catalyst, PNL is suggesting the new catalyst isn’t as efficient.   How much more so isn’t made clear.

The feedstock isn’t straight water either.  There’s a lot of amino acid (protein) involved.  The hydrogen is coming out of the amino acid not the water – thus we’re wondering what the feedstock source of the hydrogen atoms might cost.

Yet, this is a major step.  Platinum is expensive and prohibits developing water splitting for the hydrogen and is a barrier to economical fuel cells to recover the energy efficiently.  Coming out with a partial step using low cost iron and nickel is very hopeful.

Bullock offers the team has some ideas on how to increase the efficiency. Also, future work will require assembling a catalyst that splits water in addition to making hydrogen gas. Even with a high electrical overpotential, the team sees the new catalyst with great prospects for future development.

When using water, even when a not so great electrical efficiency is the result, such screaming speeds will be very attractive.  Especially if the capital cost is proportionally down to the price difference between platinum and nickel.  A chemical store of energy using hydrogen, from cheap water splitting and cheap fuel cells would be new dynamic in personal to mid-size energy production