Chemists report promising advance in fuel-cell technology

May 24, 2010
The multimetallic nanoparticle created by Brown University chemists for fuel-cell reactions uses a palladium core and an iron-platinum shell. Credit: Shouheng Sun Laboratory, Brown University

Creating catalysts that can operate efficiently and last a long time is a big barrier to taking fuel-cell technology from the lab bench to the assembly line. The precious metal platinum has been the choice for many researchers, but platinum has two major downsides: It is expensive, and it breaks down over time in fuel-cell reactions.

In a new study, chemists at Brown University report a promising advance. They have created a unique core and shell nanoparticle that uses far less platinum yet performs more efficiently and lasts longer than commercially available pure-platinum catalysts at the cathode end of reactions.

The chemistry known as oxygen reduction reaction takes place at the fuel cell's cathode, creating water as its only waste, rather than the global-warming carbon dioxide produced by internal combustion systems. The is also where up to 40 percent of a fuel cell's efficiency is lost, so "this is a crucial step in making fuel cells a more competitive technology with internal combustion engines and batteries," said Shouheng Sun, professor of chemistry at Brown and co-author of the paper in the .

The research team, which includes Brown graduate student and co-author Vismadeb Mazumder and researchers from Oak Ridge National Laboratory in Tennessee, created a five-nanometer palladium (Pd) core and encircled it with a shell consisting of iron and platinum (FePt). The trick, Mazumder said, was in molding a shell that would retain its shape and require the smallest amount of platinum to pull off an efficient reaction. The team created the iron-platinum shell by decomposing iron pentacarbonyl [Fe(CO)5] and reducing platinum acetylacetonate [Pt(acac)2], a technique Sun first reported in a 2000 Science paper. The result was a shell that uses only 30 percent platinum, although the researchers say they expect they will be able to make thinner shells and use even less platinum.

"If we don't use iron pentacarbonyl, then the platinum doesn't form on the (palladium) core," Mazumder said.

The researchers demonstrated for the first time that they could consistently produce the unique core-shell structures. In laboratory tests, the palladium/iron-platinum generated 12 times more current than commercially available pure-platinum catalysts at the same catalyst weight. The output also remained consistent over 10,000 cycles, at least ten times longer than commercially available platinum models that begin to deteriorate after 1,000 cycles.

The team created iron-platinum shells that varied in width from one to three nanometers. In lab tests, the group found the one-nanometer shells performed best.

"This is a very good demonstration that catalysts with a core and a shell can be made readily in half-gram quantities in the lab, they're active, and they last," Mazumder said. "The next step is to scale them up for commercial use, and we are confident we'll be able to do that."

Mazumder and Sun are studying why the palladium core increases the catalytic abilities of iron , although they think it has something to do with the transfer of electrons between the core and shell metals. To that end, they are trying to use a chemically more active metal than palladium as the core to confirm the transfer of electrons in the core-shell arrangement and its importance to the catalyst's function.

Explore further: New star-shaped molecule breakthrough

Related Stories

Nanoscale 'Egg' Kills Tumor Cells with Platinum

Jan 22, 2007

Researchers at the Hong Kong University of Science and Technology have developed a nanoscale “egg” that could safely deliver platinum, a known anticancer agent, to tumor cells. Tests with this nanoscale egg, which has ...

Argonne to study fuel cell catalysts

May 26, 2005

Argonne National Laboratory will receive $3 million over three years for basic science studies that may lead to improved catalysts for hydrogen fuel cells.

Replacing Platinum in Fuel Cell Technology

Oct 20, 2009

( -- One of the biggest hindrances to the development of fuel cell technology is its cost. In order to work properly, polymer electrolyte fuel cells require a catalyst. So far, though, the most ...

Recommended for you

New star-shaped molecule breakthrough

56 minutes ago

( —Scientists at The University of Manchester have generated a new star-shaped molecule made up of interlocking rings, which is the most complex of its kind ever created.

Smartgels are thicker than water

Sep 19, 2014

Transforming substances from liquids into gels plays an important role across many industries, including cosmetics, medicine, and energy. But the transformation process, called gelation, where manufacturers ...

Separation of para and ortho water

Sep 18, 2014

( —Not all water is equal—at least not at the molecular level. There are two versions of the water molecule, para and ortho water, in which the spin states of the hydrogen nuclei are different. ...

User comments : 0