## MIT Researchers Identify New Low-Cost Water-Splitting Catalyst

##### 12 May 2010

MIT Prof. Daniel Nocera and his associates have found another formulation, based on inexpensive and widely available materials, that can efficiently catalyze the splitting of water molecules using electricity. In 2008, Nocera and his team reported developing a water-splitting catalyst that is easily prepared from earth-abundant materials (cobalt and phosphorous) and operates in benign conditions: pH neutral water at room temperature and 1 atm pressure. (Earlier post.)

In a paper published this week in the journal Proceedings of the National Academy of Science (PNAS), Nocera, along with postdoctoral researcher Mircea Dincă and graduate student Yogesh Surendranath, report finding that nickel borate can also efficiently and sustainably function as the oxygen-producing electrode for water splitting. Materials for the new catalyst are even more abundant and inexpensive than those required for the first.

Thin catalyst films with electrocatalytic water oxidation properties similar to those of a recently reported Co-based catalyst can be electrodeposited from dilute Ni2+ solutions in borate electrolyte at pH 9.2 (Bi). The Ni-Bi films can be prepared with precise thickness control and operate at modest overpotential providing an alternative to the Co catalyst for applications in solar energy conversion.

—Dincă et al.

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.

This could ultimately form the basis for new storage systems that would allow buildings to be completely independent and self-sustaining in terms of energy. Nocera pictures small-scale systems in which rooftop solar panels would provide electricity, with any excess going 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.

Nocera, the Henry Dreyfus Professor of Energy and Professor of Chemistry, says that solar energy is the only feasible long-term way of meeting the world’s ever-increasing needs for energy, and that storage technology will be the key enabling factor to make sunlight practical as a dominant source of energy. He has focused his research 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. By doing so, he aims to imitate the process of photosynthesis, by which plants harvest sunlight and convert the energy into chemical form.

The research is still in an early stage. Nocera believes that as the team carries out further research even better compounds will come to light.

Already, Nocera and his team have increased the rate of production from these catalysts a hundredfold from the level they initially reported two years ago. In addition, while the earlier paper and the new report focus on electrodes on the oxygen-producing side, originally the other electrode, which produced hydrogen, included the use of a relatively expensive platinum catalyst. But in further work, “we have totally gotten rid of the platinum of the hydrogen side,” Nocera says. “That’s no longer a concern for us,” he says, although that part of the research has not yet been formally reported.

The original discovery has already led to the creation of a company, called Sun Catalytix, that aims to commercialize the system in the next two years. Nocera’s research program was recently awarded more than $4 million in funding from the US Department of Energy’s Advanced Research Projects Agency - Energy. (Earlier post.) Resources • Mircea Dincă, Yogesh Surendranath, and Daniel G. Nocera (2010) Nickel-borate oxygen-evolving catalyst that functions under benign conditions. PNAS published ahead of print doi: 10.1073/pnas.1001859107 ### Comments This sounds revolutionary! I don't know the chemistry behind the reactions, but it sounds like this could be a completely self-contained closed loop system - little or no water needed after the initial setup. You're just constantly recirculating oxygen & hydrogen and water and adding electricity and getting electricity. It would probably take in more electricity than it puts out, but if it's from wind or solar, who cares as long as it's not massive energy in, miniscule energy out. Wind farms and solar farms could set up their own electical storage & generation for 24 hour / 7 days a week load leveling with this technology. How much energy input and how long before electrodes degrade? Oil used to be one barrel in 20 barrels out, now it is one barrel in 2 barrels out. If electricity to H2 to electricity can be 50% returned that may not be so bad under certain circumstances where pumped hydro and CAES are not possible. Oil has a much bettter production ratio than one to 2. Hydrogen is very expensive to make from any kind of electricity and batteries are less expensive and more efficient at storing electricity. Vanadium redox units are quite adequate and may have even more energy density inspite of their massive tanks than hydrogen. One large unit is in operation in the US. Natural gas has so little value that it is still flared in many places not near pipelines. Hydrogen would be ignored or converted if found in the same places as natural gas as it is too expensive to transport. ..HG.. @Henry Gibson, You seem to have missed the Hawaiian scheme, which simply sends hydrogen through the natural gas network and separates it out by adsorbsion at the point of use. The cost of hydrogen other than from natural gas seems to center on about$8/kg at the moment:
http://www.h2carblog.com/?p=461

Divided by 2.5 for it's greater mileage relative to petrol you come out to around $3.50 gallon, as the link says you would have to add around$1.50 to that in the States to be revenue neutral.
So you are looking at around $5/gallon to make it worth while. Two caveats occur: a battery fuel cell hybrid would on average get far greater range and by using a fuel cell with the battery you could throw out a lot of the ICE complications. The point of this article is to reduce the cost of hydrogen production, so hopefully costs may improve per kg. My source is the "Long Emergency" which has its own references for the 1 to 2 number. Saudi Arabia has a better ratio and other countries might as well, but new drilling in deep water comes out to a ratio closer to that. Rigs can cost upwards of$1 billion and it takes energy to make, transport and operate those.

Saudi light sweet crude can be extracted for about $2/barrel. Oil from tar sands and deep wells cost tens of dollars per barrel, so it is only economical when oil prices are high. My concern with H2 from electrolysis is that you're started with a high quality product (electricity), and throwing half of it away to turn it into a more portable product, then you have all the leakage and weird storage issues with H2. The question is, is this worth creating a whole new transportation and storage infrastructure, if you could instead just put 90% of the electricity into batteries? Fuel cells are still more expensive than batteries. For structures, you could use heavy, durable, less costly batteries (Iron-Nickle?), which are probably safer than storing explosive H2. Take the electricty and put it on the grid. Need some back? Take it frim the grid. No grid near by that is big enough to handle this? Move to where there is a grid or build some power lines. Can't do either? You porbably shouldn't be there. It is not just for storage, it can be for more fuel. Biomass has lots of carbon, so if you can get H2 you can make more fuel per ton. I'd be much more inclined to use H2 for chemical feedstock than trying to use it as local battery storage. A cheap electrolysis cell which you can afford to leave idle most of the time so you can buy only really cheap off-peak power (e.g. chopping the tops off the wind-farm production curves) might make hydrogen at a price you can afford for production of things like ethylene. In the end we are talking about h2 that is cheaper per mile then gasoline in a car that is cheaper to buy then a gasoline powered car and yet is more powerful lasts longer is far more dependable and has all the range and more of a gas powered car. So realy in the end its a done deal and they all know it. They are all just trying to make it happen a bit faster or make money off it happening. Presumably this would be used for soaking up excess wind or solar or night power. The problems with H2 are storage, transport and fuel cell cost (!). So you might be better off combining it with some carbon containing feedstock to produce a liquid HC fuel, or even methane (as others have said). You could imagine moving the electric power to a coal mine to convert to Hc there and then pipe it on to the oil distribution network (or the same for gas). Or you could move it to a biomass plantation region where you could make the HCs there, thus reducing the cost of transporting bulky biomass. You definitely do not want to move the biomass any farther than you have to. So if you have gasification plants all over the farming regions you can make H2 using reversible SOFCs. Add concentrated solar thermal for the heat source and make H2 by the ton. Combine it with carbon left over from the biomass gasification and make more fuel per ton. As many commenters have already noted, efficiency will determine the efficacy of this approach. @ Will S: Efficiency does NOT matter. Economic viability matters and low environmental impact matters. Both electrical generation to use and gasoline combustion to tires involve huge losses- but these technologies can be affordably used. The same will be true of hydrogen. It should be obvious that the other problems will be solved as well, as there has been huge progress on storage, generation, and fuel cell costs. Low-cost H2 synthesis is key for future renewable energy synthetic fuels. Make synthetic methane out of H2 if a source of carbon is readily available. If no cost-effective carbon source is available, then store the H2 for use later on. Very simple. Why have to decide one fuel vs the other when we can have both? John, Efficiency is a key aspect of economic viability. If the process is only 50% efficient overall, then the economic viability is highly doubtful. Using twice as much coal-fired electricity as a battery powered EV has far too many environmental impacts. It depends on what you do with it. If you make 50 cent per therm SNG it is not profitable. If you make$3 per gallon ethanol it may be. The final analysis with PV was put it on the grid during peak times, you make more money that way and have a shorter payback period. However, if you run a car with it and save $10 in fuel, it can even make more sense rather than selling 20 kWh at$2 to the grid.

Efficiency does matter depending on the situation. You wouldn't want to carry ten tons of low cost fuel in a car to go forty miles. PV panels take roof space and wouldn't be practical at 1% efficiency even though the solar energy is free. Airplanes wouldn't get off the ground if the engines weren't efficient, no matter how cheap the fuel is. Low effiency affects the environment in all energy convesion processes, of course hydrocarbons are the worst.

Has anyone noticed the distinct lack of hard numbers associated with this report? How much more productive is this than my sticking two copper wires in a bucket of water (which is very inefficient BTW in terms of energy in to energy out)?

Methinks this is a grant-fishing proposal. Look what I can do! Give me more money and I can do more of it!

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