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Yale team develops new silver-palladium core-shell catalyst for direct alcohol fuel cells

Yale
The core-shell silver-palladium catalyst. Source: Yale. Click to enlarge.

Yale researchers have synthesized a silver-palladium core-shell catalyst supported on multi-walled carbon nanotubes (Ag@Pd/MWNTs) for use in fuel cells. The new platinum-free catalysts are are highly active and alcohol-tolerant for oxygen reduction reactions (ORR) in alkaline media. A paper on their work is published in the journal Applied Catalysis B.

The new, platinum-free catalyst has a unique core-shell structure; the thin shell is palladium, the core silver. This allows for higher catalytic activity and greater tolerance for impurities than standard platinum-based catalysts. Particles of silver coated with palladium cover the surface of multi-walled carbon nanotubes, promoting the reduction of oxygen over the oxidation of alcohol.

The Ag@Pd/MWNTs are shown to be tolerant of the presence of methanol and ethanol in the electrolyte. In the presence of methanol, the Ag@Pd/MWNTs current density decreased by 0.18 mA/cm2, compared to Pt/C (0.97 mA/cm2) and Pd/C (1.09 mA/cm2). In the presence of ethanol, the Ag@Pd/MWNTs current density decreased by 0.12 mA/cm2, compared to Pt/C (0.87 mA/cm2) and Pd/C (2.13 mA/cm2). The Ag@Pd/MWNTs also show improved durability with an increased mass activity of ∼3.5 times that of standard Pd/C, after durability testing in ethanol. The Ag@Pd/MWNTs are promising platinum free direct alcohol fuel cell cathode catalysts due to their high activities and durability, as well as their improved tolerance to methanol and ethanol from possible fuel crossover.

—Sekol et al.

Tolerance to alcohol is important due to fuel crossover in the fuel cell, which occurs by the diffusion across the membrane. Platinum has been the preferred fuel cell catalyst material, but its scarcity has prevented the widespread use of fuel cells.

The high cost of platinum and other noble metals is one of the major hurdles for the commercialization of low-temperature fuel cells. This catalyst architecture could reduce this cost by using palladium only in the shell region of the catalyst.

—André D. Taylor, principal investigator

The researchers’ technique for making the catalyst’s thin palladium shell, called galvanic displacement, could be used for fabricating new materials with properties appropriate for a wide range of other applications, such as sensors, or battery materials.

The National Science Foundation and Yale Climate Energy Initiative provided support for the research.

Resources

  • Ryan C. Sekol, Xiaokai Li, Peter Cohen, Gustavo Doubek, Marcelo Carmo, André D. Taylor (2013) Silver Palladium Core-Shell Electrocatalyst Supported on MWNTs for ORR in Alkaline Media, Applied Catalysis B: Environmental doi: 10.1016/j.apcatb.2013.02.054

Comments

kelly

A cheap, infrequent use, ethanol fuel cell might make a BEV range extender/emergency genset.

There's a lot of excitement about the ~ one-per-day Hyundai I35 fuel cell SUV production, but aren't they still over $100,000 each and without hydrogen infrastructure?

Davemart

It is called new technology.
For the same reason as we did not have airfields until we had aircraft, we have not got hydrogen filling stations until we have cars to use them.
It is all pretty logical, when you think about is.
Japan is building 100 filling stations by 2015, if that makes you feel better.
If you were producing just a few ICE cars, then they would be pretty expensive too.
It is what is known as a production ramp up.
Do you have anything half way sensible to say?

HarveyD

First FCs users could be heavy long range hybrid trucks and locomotives. They have plenty of room to fit many FC modules and fuel tanks.

Long haul heavy trucks and locomotives do not need that many fuel stations and they could share some large fuel stations. Some (7 x = 49) large stations would be enough for a first generation continental USA network.

Since those (large stations) would be good money making endeavors, many private industries would fight for the licences.

HarveyD

Correctio:....Some (7x = 49).... should read ...Some (7 x 7 = 49)....

Morningtoronto

About currently produced hydrogen FC. Elon Musk calls FC a "fools cells". And for a reason.

Anyhow, where will hydrogen will come from? Sure from natural gas and from coal. That is where 99.999% of hydrogen currently comes from.

And if someone decide to totally ignore economics and think of electrolysis from water, you can ask him why someone would need an extra middle man, hydrogen, so electricity --> hydrogen --> FC --> electricity? Instead of simply charging the batteries.

And do not forget, 2 mil $$$ for single hydrogen filing station is nothing but theoretical estimated for best cases scenario... They would cost more then $2,000,000 each. When reality will hit. Probably much more. And US would need only 130,000 such stations.

Sure what I said above is just top of the iceberg. Anyone with any intelligence should be able to go on and on. Safety, why keep highly flammable chemical that forms powerful explosions few feet from your children while driving? And hold it under insane pressure. And sure again list could go on and on. And if you could not continue this list - may be Musk's reference to fools could be applied to someone like you:)

SJC

We were just waiting for your opinions, could not live without them. An alcohol fuel cell runs on liquid alcohol, no need for pressurized tanks of hydrogen.

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