Researchers Design Nanoscale Fuel Cell Catalyst Using Less Platinum

May 15 2009 / by Garry Golden
Category: Energy   Year: General   Rating: 2 Hot

nanostructured catalyst Washington U

The nanoscale design of basic energy components is once again revealing new solutions to the historical problems of high cost alternative energy systems.

Materials scientists from Washington University in St. Louis  and Brookhaven National Laboratory have designed a nanostructured bimetallic (platinum and palladium) fuel cell catalyst that is 'efficient, robust and two-to-five times more effective than existing commercial catalysts.' 

Fuel cells are important as 21st century 'power plants' that produce electricity on demand without a grid connection. Fuel cells can be designed as small as a AA battery (for portable gadgets), a breadbox (for electric vehicles), a small refrigerator (for home power) or the size of a small room (for utility power generation). 

Commercialization of fuel cells depends on our ability to lower the costs of core membranes (MEAs) that convert chemical energy into electricity. 

So what is the way forward?  Nanostructured design of key membrane components.

Nanoscale Revolution:
Rethinking Surface Area & Shape

Team leader Professor Younan Xia explains the importance of the breakthrough:  "There are two ways to make a more effective catalyst," Xia says. "One is to control the size, making it smaller, which gives the catalyst a higher specific surface area on a mass basis. Another is to change the arrangement of atoms on the surface. We did both. You can have a square or hexagonal arrangement for the surface atoms. We chose the hexagonal lattice because people have found that it's twice as good as the square one for the oxygen reduction reaction (which determines the electrical current generated)."

To reduce costs and improve performance the team experimented with new core and branching structures. The catalyst has a core made of palladium which branching arms (‘dendrites’) of platinum that are seven nano-meters long.  

According to Xia's team release: ‘At room temperature operation the team’s catalyst was two-and-a-half times more effective per platinum mass for this process than the state of the art commercial platinum catalyst and five times more active than the other popular commercial catalyst.  At 60 degrees C (the typical operation temperature of a fuel cell), the performance almost meets the targets set by the U.S. Department of Energy.’

The next step for the team? 

Integrating gold as a third metal catalyst to deal with the problem of carbon molecules that reduces performance by binding and blocking valuable surface area.

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Carbon based hydrogen storage might be on the horizon

October 09 2008 / by Garry Golden
Category: Energy   Year: 2018   Rating: 1

Hydrogen fuel cells, which produce electricity, are an evolution to modern day batteries. If we can store hydrogen efficiently as a solid, we can expand the use of energy from intermittent solar and wind power. We can also lower the costs and improve performance of electric vehicles. Two recent research announcements hint that cost effective storage could be much closer to reality.

Nanoscale science & surface area
One of the key enablers of storing hydrogen as a solid is high surface area. How much? Can you imagine holding a gram of material with surface area equal to several football fields for storing hydrogen molecules?

Nanoscale (billionth of a meter) material design means high surface area ratio to volume. We can also tap nanotechnology to create storage materials able to bind and release hydrogen molecules at low pressure and low temperature.

Carbon scaffolding for storage
There are a number of ways to store hydrogen as a solid, and also as a liquid. Earlier we featured a look at metal-organic frameworks or MOFs as a viable long term storage material. Today we’ll look at two other carbon-based hydrogen storage systems.

Carbon is a controversial storage medium since it is ‘sticky’ and can often bind hydrogen too tightly. But mixing (or ‘doping’) carbon with other elements can leverage the benefits of carbon’s high surface area and its Lego-like structural design.

‘Doping corn cobs?’
The Department of Energy has awarded $1.9 million to researchers at the University of Missouri and Midwest Research Institute (MRI)

The Missouri team has found that carbon briquettes (derived from corn cobs) then “doped” (or mixed and layered) with boron, have a unique ability to store natural gas with high capacity at low pressure.

While corn cobs hydrogen storage sounds a bit far fetched, one gram of this carbon material has a surface area comparable to a football field. The boron additive to carbon creates binding energies with H2 molecules that might make this a viable storage medium.

Carbon Graphene Layers
Another carbon based solution was announced last week from researchers in Greece using stacked thin sheets of carbon doped with lithium.

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