Washington State U: Key improvement for fuel cells: Work improves understanding of process that improves one of the primary failure points

Fuel Cell II o72016 photo_stationary_fuel_cell

Washington State University researchers have determined a key step in improving solid oxide fuel cells (SOFCs), a promising clean energy technology that has struggled to gain wide acceptance in the marketplace.

The researchers determined a way to improve one of the primary failure points for the fuel cell, overcoming key issues that have hindered its acceptance. Their work is featured on the cover of the latest issue of Journal of Physical Chemistry C.

Fuel cells offer a clean and highly efficient way to convert the chemical energy in fuels directly into electrical energy. They are similar to batteries in that they have an anode, cathode and electrolyte and create electricity, but they use fuel to create a continuous flow of electricity.

Fuel cells can be about four times more efficient than a combustion engine because they are based on electrochemical reactions, but researchers continue to struggle with making them cheaply and efficiently enough to compete with traditional power generation sources.

An SOFC is made of solid materials, and the electricity is created by oxygen ions traveling through the fuel cell. Unlike other types of fuel cells, SOFCs don’t require the use of expensive metals, like platinum, and can work with a large variety of fuels, such as gasoline or diesel fuel.

When gasoline is used for fuel, however, a carbon-based material tends to build up in the fuel cell and stop the conversion reaction. Other chemicals, in particular sulfur, can also poison and stop the reactions.

In their study, the WSU researchers improved understanding of the process that stops the reactions. Problems most often occur at a place on the anode’s surface, called the triple-phase boundary, where the anode connects with the electrolyte and fuel.

The researchers determined that the presence of an electric field at this boundary can prevent failures and improve the system’s performance. To properly capture the complexity of this interface, they used the Center for Nanoscale Materials supercomputer at the Argonne National Laboratory to perform computations.

The researchers studied similar issues in solid oxide electrolysis cells (SOECs), which are like fuel cells that run in reverse to convert carbon dioxide and water to transportation fuel precursors.

The work provides guidance that industry can eventually use to reduce material buildup and poisoning and improve performance of SOFCs and SOECs, said Jean-Sabin McEwen, assistant professor in the Gene and Linda Voiland School of Chemical Engineering and Bioengineering, who led the project.

The research is in keeping with WSU’s Grand Challenges, a suite of research initiatives aimed at large societal issues. It is particularly relevant to the challenge of sustainable resources and its theme of energy.

Story Source:

The above post is reprinted from materials provided byWashington State University. Note: Materials may be edited for content and length.

Journal Reference:

  1. Fanglin Che, Su Ha, Jean-Sabin McEwen. Elucidating the Role of the Electric Field at the Ni/YSZ Electrode: A DFT Study. The Journal of Physical Chemistry C, 2016; 120 (27): 14608 DOI: 10.1021/acs.jpcc.6b01292

Stanford & Wisconsin Universities: New Fuel-Cell Materials Pave the Way for Practical Hydrogen-Powered Cars

New Fuel Call Materials 071715 180px-Protium_svgProtium, the most common isotope of hydrogen. Image: Wikipedia.

Hydrogen fuel cells promise clean cars that emit only water. Several major car manufacturers have recently announced their investment to increase the availability of fueling stations, while others are rolling out new models and prototypes. However, challenges remain, including the chemistry to produce and use hydrogen and oxygen gas efficiently. Today, in ACS Central Science, two research teams report advances on chemical reactions essential to fuel-cell technology in separate papers.

Hydrogen (H2) fuel cells react H2 and oxygen (O2) gases to produce energy. For that to happen, several related are needed, two of which require catalysts. The first step is to produce the two gases separately. The most common way to do that is to break down, or “split,” water with an electric current in a process called electrolysis. Next, the must promote the oxidation of H2. That requires reduction of O2, which yields water. The catalysts currently available for these reactions, though, are either too expensive and demand too much energy for practical use, or they produce undesirable side products. So, Yi Cui’s team at Stanford University and James Gerken and Shannon Stahl at the University of Wisconsin, Madison, independently sought new materials for these reactions.

Honda's Next Generation Solar Hydrogen Station PrototypeCui’s group worked on the first reaction, developing a new cadre of porous materials for water splitting. They notably used earth abundant metal oxides, which are inexpensive. The oxides also are very stable, undergoing the reaction in for 100 hours, significantly better than what researchers have reported for other non-precious metal materials. On the side of oxygen reduction, Gerken and Stahl show how a catalyst system commonly used for aerobic oxidation of organic molecules could be co-opted for electrochemical O2 reduction. Despite the complementary aims, the two studies diverge in their approaches, with the Stanford team showcasing rugged oxide materials, while the UW-Madison researchers exploited the advantages of inexpensive metal-free molecular catalysts. Together these findings demonstrate the power and breadth of chemistry in moving fuel-cell technology forward.

More information: The two papers will be freely available July 15, 2015, at these links:

“In Situ Electrochemical Oxidation Tuning of Transition Metal Disulfides to Oxides for Enhanced Water Oxidation” pubs.acs.org/doi/full/10.1021/acscentsci.5b00163

“High-Potential Electrocatalytic O2 Reduction with Nitroxyl/NOx Mediators: Implications for Fuel Cells and Aerobic Oxidation Catalysis” pubs.acs.org/doi/full/10.1021/acscentsci.5b00227

NIST’s ‘Nano-Raspberries’ Could Bear Fruit in Fuel Cells

Researchers at the National Institute of Standards and Technology (NIST) have developed a fast, simple process for making platinum “nano-raspberries”—microscopic clusters of nanoscale particles of the precious metal. The berry-like shape is significant because it has a high surface area, which is helpful in the design of catalysts. Even better news for industrial chemists: the researchers figured out when and why the berry clusters clump into larger bunches of “nano-grapes.”

Colorized micrographs of platinum nanoparticles made at NIST. The raspberry color suggests the particles’ corrugated shape, which offers high surface area for catalyzing reactions in fuel cells. Individual particles are 3-4 nm in diameter but can clump into bunches of 100 nm or more under specific conditions discovered in a NIST study.
Credit: Curtin/NIST
View hi-resolution image

The research could help make fuel cells more practical. Nanoparticles can act as catalysts to help convert methanol to electricity in fuel cells. NIST’s 40-minute process for making nano-raspberries, described in a new paper,* has several advantages. The high surface area of the berries encourages efficient reactions. In addition, the NIST process uses water, a benign or “green” solvent. And the bunches catalyze methanol reactions consistently and are stable at room temperature for at least eight weeks.

Although the berries were made of platinum, the metal is expensive and was used only as a model. The study will actually help guide the search for alternative catalyst materials, and clumping behavior in solvents is a key issue. For fuel cells, nanoparticles often are mixed with solvents to bind them to an electrode. To learn how such formulas affect particle properties, the NIST team measured particle clumping in four different solvents for the first time. For applications such as liquid methanol fuel cells, catalyst particles should remain separated and dispersed in the liquid, not clumped.

“Our innovation has little to do with the platinum and everything to do with how new materials are tested in the laboratory,” project leader Kavita Jeerage says. “Our critical contribution is that after you make a new material you need to make choices. Our paper is about one choice: what solvent to use. We made the particles in water and tested whether you could put them in other solvents. We found out that this choice is a big deal.”

The NIST team measured conditions under which platinum particles, ranging in size from 3 to 4 nanometers (nm) in diameter, agglomerated into bunches 100 nm wide or larger. They found that clumping depends on the electrical properties of the solvent. The raspberries form bigger bunches of grapes in solvents that are less “polar,” that is, where solvent molecules lack regions with strongly positive or negative charges. (Water is a strongly polar molecule.)

The researchers expected that. What they didn’t expect is that the trend doesn’t scale in a predictable way. The four solvents studied were water, methanol, ethanol and isopropanol, ordered by decreasing polarity. There wasn’t much agglomeration in methanol; bunches got about 30 percent bigger than they were in water. But in ethanol and isopropanol, the clumps got 400 percent and 600 percent bigger, respectively—really humongous bunches. This is a very poor suspension quality for catalytic purposes.

Because the nanoparticles clumped up slowly and not too much in methanol, the researchers concluded that the particles could be transferred to that solvent, assuming they were to be used within a few days—effectively putting an  expiration date on the catalyst.

Two college students in NIST’s Summer Undergraduate Research Fellowship (SURF) program helped with the extensive data collection required for the study.

* I. Sriram, A.E. Curtin, A.N. Chiaramonti, J.H. Cuchiaro, A.D. Weidner, T.M. Tingley, L.F. Greenlee and K.M. Jeerage. Stability and phase transfer of catalytically active platinum nanoparticle suspensions. Journal of Nanoparticle Research 17:230.DOI 10.1007/s11051-015-3034-1. Published online May 22, 2015.

Annual Merit Review Evaluates Impact of Sustainable Transportation Projects

Transportation Merit Reviewargonne%20test%20vehicleDid you know that there are experts who evaluate the Energy Department’s work to see if projects really are transforming clean energy economy in sectors like transportation? To gather feedback from the research community, many programs across the Department have annual merit or peer reviews where scientific experts rate projects for their value.  This week from June 8 to 12, the Vehicle Technologies Office and Hydrogen and Fuel Cells Program are simultaneously holding their Annual Merit Review and Peer Evaluation Meeting in Washington, D.C., where hundreds of Energy Department-funded projects will be put to the test.

To cover almost all of the work funded by the Vehicle and Fuel Cell Technologies Offices reviewers will judge nearly 400 individual activities. The reviewers come from a variety of backgrounds, including current and former members of the vehicles industry, academia, national laboratories, and government. From back-to-back presentations to poster sessions, the days are intellectually demanding, requiring intense focus and analysis of highly technical projects.

But the valuable feedback will make the challenge worth it.  Each reviewer evaluates a set of projects based on how much they contribute to or advance the Energy Department’s missions and goals. The reviewer considers the project’s breadth, depth, appropriateness, accomplishments, and potential.  Considering the short and long-term benefits, he or she judges the project based on a standard set of defined metrics. Reviewers provide numeric scores and in-depth comments, creating a comprehensive project report card. After the review, the offices carefully consider the reviewers’ recommendations as they generate work plans, create long-term strategies, and formulate budgets.

Open to the public and free of charge, the Annual Merit Review and Peer Evaluation Meeting provides a great opportunity for those interested in the Energy Department’s research, development, and deployment activities in transportation to learn about the relevant programs. Merit reviews also serve two other valuable purposes: increasing transparency and building a vibrant research community.

Can’t attend? The offices will post the presentations to their websites a few weeks after the meeting.  In fact, presentations from past merit reviews are available on the Vehicle Technologies Office website and the Hydrogen and Fuel Cells Program website. About three to four months after the review, the programs also post reports with the results of the review.

Because the reviews bring together breadth and depth of energy experts, they allow researchers in industry, academia, and government to learn about others’ projects.  They help scientists see where their work intersects, enabling them to collaborate more effectively. They also facilitate the movement of technology from the government, labs, and universities into the private sector, which can bring them to market.

Merit and peer reviews are invaluable to the government, public and industry.  They help keep projects on the right track and drive innovation forward.  While the Vehicle Technologies Office and Hydrogen and Fuel Cell 2015 Annual Merit Review and Peer Evaluation meeting is only this week, it will have a positive impact for the clean energy economy of tomorrow. Find out more about the projects being reviewed by following us on Twitter with the hashtags #VTOAMR and #H2AMR.

Nanotechnology in Fuel Cells

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How can nanotechnology improve fuel cells?

 *** From UnderstandingNano.com ***

Catalysts are used with fuels such as hydrogen or methanol to produce hydrogen ions. Platinum, which is very expensive, is the catalyst typically used in this process. Companies are using nanoparticles of platinum to reduce the amount of platinum needed, or using nanoparticles of other materials to replace platinum entirely and thereby lower costs.

Fuel cells contain membranes that allow hydrogen ions to pass through the cell but do not allow other atoms or ions, such as oxygen, to pass through. Companies are using nanotechnology to create more efficient membranes; this will allow them to build lighter weight and longer lasting fuel cells.

Small fuel cells are being developed that can be used to replace batteries in handheld devices such as PDAs or laptop computers. Most companies working on this type of fuel cell are using methanol as a fuel and are calling them DMFC’s, which stands for direct methanol fuel cell. DMFC’s are designed to last longer than conventional batteries. In addition, rather than plugging your device into an electrical outlet and waiting for the battery to recharge, with a DMFC you simply insert a new cartridge of methanol into the device and you’re ready to go.

Fuel cells that can replace batteries in electric cars are also under development. Hydrogen is the fuel most researchers propose for use in fuel cell powered cars. In addition to the improvements to catalysts and membranes discussed above, it is necessary to develop a lightweight and safe hydrogen fuel tank to hold the fuel and build a network of refueling stations. To build these tanks, researchers are trying to develop lightweight nanomaterials that will absorb the hydrogen and only release it when needed. The Department of Energy is estimating that widespread usage of hydrogen powered cars will not occur until approximately 2020.

Fuel Cells: Nanotechnology Applications

Researchers at the University of Copenhagen have demonstrated the ability to significantly reduce the amount of platinum needed as a catalyst in fuel cells.  The researchers found that the spacing between platinum nanoparticles affected the catalytic behavior, and that by controlling the packing density of the platinum nanoparticles they could reduce the amount of platinum needed.

Researchers at Brown University are developing a catalyst that uses no platinum. The catalyst is made from a sheet of graphene coated with cobalt nanoparticles. If this catalyst works out for production use with fuel cells it should be much less expensive than platinum based catalysts.

Researchers at Ulsan National Institute of Science and Technology have demonstrated how to produce edge-halogenated graphene nanoplatelets that have good catalytic properties. The researchers prepared the nanoplatelets by ball-milling graphene flakes in the presence of chlorine, bromine or iodine. They believe these halogenated nanoplatelets could be used as a replacement for expensive platinum catalystic material in fuel cells.

Researchers at Cornell University have developed a catalyst using platinum-cobalt nanoparticles that produces 12 times more catalytic activity than pure platinum. In order to achieve this performance the researchers annealed the nanoparticles so they formed a crystalline lattice which reduced the spacing between platinum atoms on the surface, increasing their reactivity.

Researchers at the University of Illinois have developed a proton exchange membrane using a silicon layer with pores of about 5 nanometers in diameter capped by a layer of porous silica. The silica layer is designed to insure that water stays in the nanopores. The water combines with the acid molecules along the wall of the nanopores to form an acidic solution, providing an easy pathway for hydrogen ions through the membrane. Evaluation of this membrane showed it to have much better conductivity of hydrogen ions (100 times better conductivity was reported) in low humidity conditions than the membrane normally used in fuel cells.

Researchers at Rensselaer Polytechnic Institute have investigated the storage of hydrogen in graphene (single atom thick carbon sheets). Hydrogen has a high bonding energy to carbon, and the researchers used annealing and plasma treatment to increase this bonding energy. Because graphene is only one atom thick it has the highest surface area exposure of carbon per weight of any material. High hydrogen to carbon bonding energy and high surface area exposure of carbon gives graphene has a good chance of storing hydrogen. The researchers found that they could store14% by weight of hydrogen in graphene.

Researchers at Stony Brook University have demonstrated that gold nanoparticles can be very effective at using solar energy to generate hydrogen from water. The key is making the nanoparticles very small. They found that  nanoparticles containing less than a dozen gold atoms are very effective photocatalysts for the generation of hydrogen.goldstand

Researchers at the SLAC National Accelerator Laboratory have developed a way to use less platinum for the cathode in a fuel cell, which could significantly reduce the cost of fuel cells. They alloyed platinum with copper and then removed the copper from the surface of the film, which caused the platinum atoms to move closer to each other (reducing the lattice space). It turns out that platinum with reduced lattice spacing is more a more effective catalyst for breaking up oxygen molecules into oxygen ion. The difference is that the reduced spacing changes the electronic structure of the platinum atoms so that the separated oxygen ions more easily released, and allowed to react with the hydrogen ions passing through the proton exchange membrane.

Another way to reduce the use of platinum for catalyst in fuel cell cathodes is being developed by researchers at Brown University. They deposited a one nanometer thick layer of platinum and iron on spherical nanoparticles of palladium. In laboratory scale testing they found that an catalyst made with these nanoparticles generated 12 times more current than a catalyst using pure platinum, and lasted ten times longer. The researchers believe that the improvement is due to a more efficient transfer of electrons than in standard catalysts.

Increasing catalyst surface area and efficiency by depositing platinum on porous alumina

Allowing the use of lower purity, and therefore less expensive, hydrogen with an anode made made of platinum nanoparticles deposited on titanium oxide.

Replacing platinum catalysts with less expensive nanomaterials

Using hydrogen fuel cells to power cars

Using nanostructured vanadium oxide in the anode of solid oxide fuel cells. The structure forms a battery, as well a fuel cell, therefore the cell can continue to provide electric current after the hydrogen fuel runs out.

Fuel Cells: Nanotechnology Company Directory

Company Product Advantage
QuantumSphere Non-platinum catalyst Reduces cost
MTI Micro DMFC’s Minimizes moving parts, reduces cost, size and weight
UltraCell DMFC’s that uses an extra catalyst to convert methanol to hydrogen before reaching the core of the fuel cell Increases power density and cell voltage
EDC Ovonics Hydrogen fuel tanks using metal hydrides as the storage media Reduce size, weight and pressure for storing hydrogen
Unidym Carbon nanotube based electrodes Improve efficiency of fuel cells by reducing resistive and mass transfer losses
GridShift Hydrogen generation using nanoparticle coated electrodes Improve efficiency of hydrogen generation by electrolysis
Aerogel Composite Catalyst with platinum nanoparticles embedded in a carbon aerogel Reduces platinum usage

Fuel Cell Resources

Hydrogen, Fuel Cells & Infrastructure Technologies Program at DOE

National Hydrogen Energy Roadmap

National Fuel Cell Research Center

California Fuel Cell Partnership

Department of Energy Hydrogen Permitting Web site

Listing of Hydrogen Fueling Station Location Worldwide

Making Fuel Cell Technology Cheaper: Insights into Potential Substitutes for Costly Platinum in Fuel Cell Catalysts

Fule Cells 041415 insightsintoPlatinum’s scarcity hinders widespread use of fuel cells, which provide power efficiently and without pollutants. Replacing some or all of this rare and expensive metal with common metals in a reactive, highly tunable nanoparticle form may expand fuel cell use. At Pacific Northwest National Laboratory, scientists made such metal nanoparticles with a new gas-based technique and ion soft landing. As an added benefit, the particles are bare, without a capping layer that coats their surfaces and reduces their reactivity.

Replacing inefficient and polluting combustion engines with fuel cells is not currently feasible because the cells require platinum-based catalysts. The PNNL study shows how to create particles with a similar reactivity to platinum that replace some of the platinum with Earth-abundant metals. The implications of this new preparation technique go far beyond fuel cells. It may be used to create alloy nanomaterials for solar cells, heterogeneous catalysts for a variety of chemical reactions, and energy storage devices.

“The new method gives scientists fine control over the composition and morphology of the alloy on surfaces,” said Dr. Grant Johnson, a PNNL physical chemist who led the study.

Fule Cells 041415 insightsinto

Scientists at Pacific Northwest National Laboratory created metal alloy particles using a technique that involves magnetron sputtering and gas aggregation. They placed them on a surface using ion soft landing techniques. Credit: Johnson et …more

The team created the nanoparticles using magnetron sputtering and gas aggregation. They placed them on a surface using ion soft landing techniques devised at PNNL. The result is a layer of bare nanoparticles made from two different metals that is free of capping layers, residual reactants, and solvent molecules that are unavoidable with particles synthesized in solution.

The process begins when the scientists load 1-inch-diameter metal discs into an instrument that combines particle formation and ion deposition. Once the metals are locked into a vacuum chamber in the aggregation region, argon gas is introduced. In the presence of a large voltage the argon becomes ionized and vaporizes the metals through sputtering. The metal ions travel through a cooled region where they collide with each other and stick together. The result is bare ionic that are about 4 to 10 nanometers across. The mass spectrometer filters the ionic particles, removing those that don’t meet the desired size. The filtered particles are then soft landed onto a surface of choice, such as glassy carbon, a commonly used electrode material.

Creating the alloy particles in the gas phase provides a host of benefits. The conventional solution-based approach often results in clumps of the different metals, rather than homogeneous nanoparticles with the desired shape. Further, the particles lack a capping layer. This eliminates the need to remove these layers and clean the particles, which makes them more efficient to use.

“An important benefit is that it allows us to skirt certain thermodynamic limitations that occur when the particles are created in solution,” said Johnson. “This allows us to create alloys with consistent elemental constituents and conformation. Furthermore, the kinetically limited gas-phase approach also enables the deposition of intermediate species that would react away in solution.”

The coverage of the resulting surface is controlled by how long the particles are aimed at the surface and the intensity of the ion beam. At relatively short time frames on flat surfaces, the nanoparticles bind randomly. Leave the process running longer and a continuous film forms. Stepped surfaces result in the nanoparticles forming linear chains on the step edges at low coverage. With longer times and a surface with defects, the particles cluster on the imperfections, providing a way to tailor surfaces with particle-rich areas and adjacent open spaces. The characterization experiments were done using the atomic force microscope, scanning and transmission electron microscopes, as well as other tools in DOE’s EMSL, a national scientific user facility.

While this work focuses on single nanoparticles, the final result is an extended array with implications that stretch from the atomic scale to the mesoscale. “Mesoscale research is about how things work together in extended arrays,” said Johnson, “and, that’s exactly what we’ve successfully built here.”

The researchers are now exploring different metal combinations with various platinum ratios to get the desired characteristics for catalysts. They plan on further studying these particles in the new in situ transmission electron microscope, planned to open in EMSL in 2015, to understand how the evolve in reactive environments.

Explore further: New nanomaterials will boost renewable energy