Electricity from seawater: New method efficiently produces hydrogen peroxide for fuel cells

 

Scientists have used sunlight to turn seawater (H₂O) into hydrogen peroxide (H₂O₂), which can then be used in fuel cells to generate electricity. It is the first photocatalytic method of H₂O₂ production that achieves a high enough efficiency so that the H₂O₂ can be used in a fuel cell.

The researchers, led by Shunichi Fukuzumi at Osaka University, have published a paper on the new method of the photocatalytic production of hydrogen peroxide in a recent issue of Nature Communications.

“The most earth-abundant resource, seawater, is utilized to produce a solar fuel that is H₂O₂,” Fukuzumi told Phys.org.

The biggest advantage of using liquid H₂O₂ instead of gaseous hydrogen (H₂), as most fuel cells today use, is that the liquid form is much easier to store at high densities. Typically, H₂ gas must be either highly compressed, or in certain cases, cooled to its liquid state at cryogenic temperatures. In contrast, liquid H₂O₂ can be stored and transported at high densities much more easily and safely.

The problem is that that, until now, there has been no efficient photocatalytic method of producing liquid H₂O₂. (There are ways to produce H₂O₂ that don’t use sunlight, but they require so much energy that they are not practical for use in a method whose goal is to produce energy.)

In the new study, the researchers developed a new photoelectrochemical cell, which is basically a solar cell that produces H₂O₂. When sunlight illuminates the photocatalyst, the photocatalyst absorbs photons and uses the energy to initiate chemical reactions (seawater oxidation and the reduction of O₂) in a way that ultimately produces H₂O₂.

After illuminating the cell for 24 hours, the concentration of H₂O₂ in the seawater reached about 48 mM, which greatly exceeds previous reported values of about 2 mM in pure water. Investigating the reason for this big difference, the researchers found that the negatively charged chlorine in seawater is mainly responsible for enhancing the photocatalytic activity and yielding the higher concentration.

Overall, the system has a total solar-to-electricity efficiency of 0.28%. (The photocatalytic production of H₂O₂ from seawater has an efficiency of 0.55%, and the fuel cell has an efficiency of 50%.)

Although the total efficiency compares favorably to that of some other solar-to-electricity sources, such as switchgrass (0.2%), it is still much lower than the efficiency of conventional solar cells. The researchers expect that the efficiency can be improved in the future by using better materials in the photoelectrochemical cell, and they also plan to find methods to reduce the cost of production.

“In the future, we plan to work on developing a method for the low-cost, large-scale production of H₂O₂ from seawater,” Fukuzumi said. “This may replace the current high-cost production of H₂O₂ from H₂ (from mainly natural gas) and O₂.”

Explore further: How does an enzyme detoxify the cells of living beings?

More information: Kentaro Mase et al. “Seawater usable for production and consumption of hydrogen peroxide as a solar fuel.” Nature Communications. DOI: 10.1038/ncomms11470

Journal reference: Nature Communications

 

Lockheed Martin Achieves Patent for Perforene™ Filtration Solution, Moves Closer to Affordable Water Desalination

BALTIMORE, March 18, 2013 – Lockheed Martin [NYSE: LMT] has been awarded a patent for Perforene™ material, a molecular filtration solution designed to meet the growing global demand for potable water.

The Perforene material works by removing sodium, chlorine and other ions from sea water and other sources.

“Access to clean drinking water is going to become more critical as the global population continues to grow, and we believe that this simple and affordable solution will be a game-changer for the industry,” said Dr. Ray O. Johnson, senior vice president and chief technology officer of Lockheed Martin. “The Perforene filtration solution is just one example of Lockheed Martin’s efforts to apply some of the advanced materials that we have developed for our core markets, including aircraft and spacecraft, to global environmental and economic challenges.”

The Perforene membrane was developed by placing holes that are one nanometer or less in a graphene membrane. These holes are small enough to trap the ions while dramatically improving the flow-through of water molecules, reducing clogging and pressure on the membrane.

At only one atom thick, graphene is both strong and durable, making it more effective at sea water desalination at a fraction of the cost of industry-standard reverse osmosis systems.

In addition to desalination, the Perforene membrane can be tailored to other applications, including capturing minerals, through the selection of the size of hole placed in the material to filter or capture a specific size particle of interest. Lockheed Martin has also been developing processes that will allow the material to be produced at scale.

The company is currently seeking commercialization partners.

The patent was awarded by the United States Patent and Trademark Office.

Headquartered in Bethesda, Md., Lockheed Martin is a global security and aerospace company that employs about 120,000 people worldwide and is principally engaged in the research, design, development, manufacture, integration and sustainment of advanced technology systems, products and services.  The Corporation’s net sales for 2012 were $47.2 billion.

A new approach to water desalination

Published on Jul  2, 2012

The availability of fresh water is dwindling in many parts of the world, a problem that is expected to grow with populations. One promising source of potable water is the world’s virtually limitless supply of seawater, but so far desalination technology has been too expensive for widespread use.

 

Now, MIT researchers have come up with a new approach using a different kind of filtration material: sheets of graphene, a one-atom-thick form of the element carbon, which they say can be far more efficient and possibly less expensive than existing desalination systems.

Read more at MIT News: http://web.mit.edu/newsoffice/2012/gr…

 

Nanotechnology key to new Desalination System

(Nanowerk News) The scarcity of fresh water is an  increasingly serious problem around the world due to growing populations and  diminishing supplies of fresh water. Desalination could help alleviate these  shortages, but it has traditionally been an extremely expensive process.

The demand for water is so great that the worldwide desalination  market is expected to reach an astonishing $87.8 billion by 2016, even though  only about 1 percent of the world’s drinking water is produced by desalination.  There is a huge need for technologies that could reduce this cost.

To help meet this need, the Innovation Fund, the University of  Chicago’s venture philanthropic proof-of-concept fund, awarded Heinrich Jaeger, the William J. Friedman and Alicia Townsend  Professor of Physics at the University of Chicago, $65,000 in its third round of  funding at the end of 2011 to establish the commercial feasibility of a  nanoparticle desalination system that Jaeger invented.

A  grant from the University of Chicago’s Innovation Fund will help Heinrich  Jaeger, PhD, establish the commercial feasibility of a nanoparticle desalination  system.

“In order for desalination to become a real solution to the  growing water scarcity problem, new technologies will be required to reduce the  major cost components of the process,” says Sean Sheridan, an assistant director  at UChicagoTech, which administers the Innovation Fund. “Professor Jaeger’s  nanofiltration technology represents a promising step towards achieving this  goal.”

The high cost of traditional desalination is driven by the price  of energy for high-pressure systems and the capital cost of high-pressure pumps  and seals. Today, recovery of capital and electric power add up to as much as  73% of the cost of desalinated water.

“Our system has the potential to cut these costs by using an  ultrathin self-assembled nanoparticle membrane,” Jaeger says. “Due to its  extreme thinness and excellent permeability characteristics, this nanofiltration  membrane can be used for a wide range of nanofiltration processes at low  pressures, including desalination.”

The nanofiltration membrane was developed by Jaeger and Xiao-Min  Lin, scientist at Argonne’s Center for Nanoscale Materials, together with  University of Chicago postdocs Jinbo He, Edward Barry and Sean McBride. At about  30 nanometers, it is the world’s thinnest and has unique features that may turn  out to make the crucial difference with this technology. The size, shape and  chemical structure of the membrane’s pores can be systematically tuned to  optimize its filtration properties. As a result, it allows 100 times more flow  at the same pressure. In addition, the self-assembly process used to fabricate  it reduces costs.

UChicagoTech’s role

Jaeger has a close working relationship with UChicagoTech, which  is committed to supporting University faculty as they work to translate bench  science to commercial applications. He regularly updates the office on his new  ideas and research results. After he approached UChicagoTech with his initial  data about the nanofiltration system, UChicagoTech helped him to develop a  business proposal and present the opportunity to the Innovation Fund.  UChicagoTech also filed an international patent application at the end of 2012  to protect the technology.

“The Innovation Fund award has been extremely helpful by giving  us not only financial support to further develop this technology in a timely  manner but also by connecting us with a highly supportive group of industry  experts and entrepreneurs,” Jaeger says.

The award is helping to optimize the low-pressure ion  rejection/permeation characteristics for the product; develop and test a system  that is environmentally friendly, compatible with drinking water standards, and  scalable for the production of large volumes of water; and design an assembly  process that is compatible with existing commercial filtration systems.

Initially, Jaeger intends to target small, distributed or mobile  water treatment systems. After being proven on a small scale, the technology  could attract additional funding and be developed for larger systems.

“The potential of this technology to establish a new class of  nanofiltration devices is an exciting prospect,” Jaeger says. “Many purification  processes in a wide range of industries depend on nanofiltration and could  benefit greatly from highly specialized and tunable parameters in a low-pressure  technology. UChicagoTech’s help has been indispensible.”

Source: By Greg Borzo, University of Chicago

Read more: http://www.nanowerk.com/news2/newsid=29442.php#ixzz2bEPuwE4i

Chemists work to desalt the ocean for drinking water, 1 nanoliter at a time

(Nanowerk News) By creating a small electrical field  that removes salts from seawater, chemists at The University of Texas at Austin  and the University of Marburg in Germany have introduced a new method for the  desalination of seawater that consumes less energy and is dramatically simpler  than conventional techniques. The new method requires so little energy that it  can run on a store-bought battery.

The process evades the problems confronting current desalination  methods by eliminating the need for a membrane and by separating salt from water  at a microscale.

The technique, called electrochemically mediated seawater  desalination, was described last week in the journal Angewandte Chemie (“Electrochemically Mediated Seawater  Desalination”). The research team was led by Richard Crooks of The  University of Texas at Austin and Ulrich Tallarek of the University of Marburg.  It’s patent-pending and is in commercial development by startup company Okeanos  Technologies.

The  left panel shows the salt (which is tagged with a fluorescent tracer) flowing  upward after a voltage is applied by an electrode (the dark rectangle) jutting  into the channel at just the point where it branches. In the right panel no  voltage is being applied. (Image: Kyle Knust)

“The availability of water for drinking and crop irrigation is  one of the most basic requirements for maintaining and improving human health,”  said Crooks, the Robert A. Welch Chair in Chemistry in the College of Natural  Sciences. “Seawater desalination is one way to address this need, but most  current methods for desalinating water rely on expensive and easily contaminated  membranes. The membrane-free method we’ve developed still needs to be refined  and scaled up, but if we can succeed at that, then one day it might be possible  to provide fresh water on a massive scale using a simple, even portable,  system.”

This new method holds particular promise for the water-stressed  areas in which about a third of the planet’s inhabitants live. Many of these  regions have access to abundant seawater but not to the energy infrastructure or  money necessary to desalt water using conventional technology. As a result,  millions of deaths per year in these regions are attributed to water-related  causes.

“People are dying because of a lack of freshwater,” said Tony  Frudakis, founder and CEO of Okeanos Technologies. “And they’ll continue to do  so until there is some kind of breakthrough, and that is what we are hoping our  technology will represent.”

To achieve desalination, the researchers apply a small voltage  (3.0 volts) to a plastic chip filled with seawater. The chip contains a  microchannel with two branches. At the junction of the channel an embedded  electrode neutralizes some of the chloride ions in seawater to create an “ion  depletion zone” that increases the local electric field compared with the rest  of the channel. This change in the electric field is sufficient to redirect  salts into one branch, allowing desalinated water to pass through the other  branch.

“The neutralization reaction occurring at the electrode is key  to removing the salts in seawater,” said Kyle Knust, a graduate student in  Crooks’ lab and first author on the paper.

Like a troll at the foot of the bridge, the ion depletion zone  prevents salt from passing through, resulting in the production of freshwater.

Thus far Crooks and his colleagues have achieved 25 percent  desalination. Although drinking water requires 99 percent desalination, they are  confident that goal can be achieved.

“This was a proof of principle,” said Knust. “We’ve made  comparable performance improvements while developing other applications based on  the formation of an ion depletion zone. That suggests that 99 percent  desalination is not beyond our reach.”

The other major challenge is to scale up the process. Right now  the microchannels, about the size of a human hair, produce about 40 nanoliters  of desalted water per minute. To make this technique practical for individual or  communal use, a device would have to produce liters of water per day. The  authors are confident that this can be achieved as well.

If these engineering challenges are surmounted, they foresee a  future in which the technology is deployed at different scales to meet different  needs.

“You could build a disaster relief array or a municipal-scale  unit,” said Frudakis. “Okeanos has even contemplated building a small system  that would look like a Coke machine and would operate in a standalone fashion to  produce enough water for a small village.”

Source: McGill University

Read more: http://www.nanowerk.com/news2/newsid=31072.php#ixzz2XZnuQSxT

Lockheed Martin moves beyond weapons to clean water with graphene

 

ERIC PIERMONT/AFP/GettyImages

Visitors look at the Lockheed Martin’s stand at the Eurosatory 2012 defence and security exhibition in Villepinte near Paris on June 11, 2012.

Defense contractor Lockheed Martin has discovered a way to make desalination 100 times more efficient. And that could have a big impact on bringing clean drinking water to the developing world.

The process is called reverse osmosis, and the material used is graphene — a lot like the stuff you smudge across paper with your pencil.

“This stuff is so thin and so strong, it’s a remarkable compound, it is one atom thick,” says Lockheed Martin senior engineer John Stetson. “If you have a piece of paper that represents the thickness of graphene, the closest similar membrane is about the height of a room.”

The new material essentially acts as a sieve, allowing water to pass though while salts remain behind. Graphene could make for smaller, cheaper plants that turn salt water into drinking water, but it could also have uses in war zones as a portable water desalinator.

“Lockheed really is concerned with the broadest aspects of global security [and] maintaining safe environments and that includes water,” says Stetson.

 

9 Incredible Uses for Graphene

Graphene is amazing. Or at least, it could be. Made from a layer of carbon one-atom thick, it’s the strongest material in the world, it’s completely flexible, and it’s more conductive than copper. Discovered just under a decade ago, the supermaterial potentially has some unbelievable applications for us in the not so distant future. All of these are just hypothetical at this point, but could be real before we know it.

And they’re all flippin incredible!

Water, water everywhere and EVERY drop drinkable. MIT minds have a plan for a graphene filter covered in tiny holes just big enough to let water through and small enough to keep salt out, making salt water safe for consumption.

Mega-fast uploads. We’re talking a whole terabit in just one second.

Plug your phone in for five seconds and it would be all charged up. The downside here is that you won’t be able to use a dead phone as an excuse anymore.

What if we actually had a clear solution for cleaning up the tainted water near Fukushima? Scientists at Rice say graphene could potentially clump together radioactive waste, making disposal is a breeze.

Graphene could pave the way for bionic devices in living tissues that could be connected directly to your neurons. So people with spinal injuries, for example, could re-learn how to use their limbs.

It could improve your tennis game, thanks to special racquets from HEAD that aim to put the weight where it’s more useful: in the head and the grip.

Touchscreens that use graphene as their conductor could be slapped onto plastic rather than glass. That would mean super thin, unbreakable touchscreens and never worrying about shattering your phone ever again.

High-power graphene supercapacitors would make batteries obselete.

Just a single sheet of graphene could produce headphones that have a frequency response comparable to a pair of Sennheisers, as some scientists at UC Berkeley recently showed us.