Platinum nanocage spheres.

Reducing the Cost of Fuel Cells

February / March 2009 By: Krista Edmonds Volume 7 Number 1

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Last September, gasoline hit $5 a gallon. Was anyone hiding under a rock during that spike? Did anyone miss the warning of how vulnerable we are in our current systems of energy consumption, whether for transportation, living comfort (light, heat, cooking, etc.), or national security? So, can we assume that we're all agreed that domestic sources of renewable, alternative energy are sorely needed—€”now?

With the increasing vulnerability, costs and negative environmental impact associated with fossil fuel use, hydrogen-powered fuel cells are an attractive alternative. Most fuel cells use platinum or platinum alloys as catalysts; unfortunately, the limited supply and the cost of platinum is a barrier to widespread fuel cell use. Therefore, more durable, efficient and inexpensive catalysts are required before fuel cells can be a practical solution to the growing energy crisis.

Fortunately, the benefits of metal nanomaterials are just beginning to be realized. New opportunities are presenting themselves in solar cells, sensors, electronics and catalysts. One promising development is the use of nanoscience to manipulate the size and shape of the platinum structure to design high-quality platinum electro-catalysts.

Researchers at Sandia National Laboratories have developed innovative methods of producing platinum catalysts with much greater control over the functional properties of platinum nanostructures. These highly efficient catalysts are expected to reduce the amount of platinum needed and thus reduce the cost of platinum catalysts for use in fuel cells, solar cells and other applications. These platinum nanomaterials promise to dramatically reduce costs and improve the efficiency and durability of hydrogen fuel cells and other renewable energy technologies. These advances in fuel cell catalysts can also lead to improved energy security for the United States.

According to John Shelnutt of Sandia, and his associates Yujiang Song and Frank von Swol, nanoscience also offers new approaches to addressing many of the U.S.'s energy challenges through tailoring materials to meet specific needs beyond fuel cells, such as more efficient solar cells, new lubricants and strong, lightweight structural materials. In addition, being able to build these materials one atom at a time, they can be designed with catalytic, electrical or optical properties that can be designed to meet specific economic and security needs of the nation. This can lead to significant improvements in many critical technology areas, including solar energy conversion, catalysts for fuel and chemical production, energy-efficient lighting, chemical and biological sensing devices and other advanced systems.

Sandia's innovations produce nanoscale platinum that possesses high electroactive surface areas, making it especially attractive for electro-catalytic applications. In fact, the large surface areas of the materials, including globular dendrites, dendritic sheets in the form of individual circular sheets or cages and foam-like spheres, and wire networks may also apply to rare metals such as palladium and platinum alloys.

The surface areas of Sandia-developed platinum nanowire networks are the highest reported at this time for unsupported platinum nanomaterials. This large surface area results from its extremely small features—€”approximately 2 nanometers across.

The synthetic processes use common, environmentally benign materials and are amenable to commercial-scale production of these catalysts for hydrogen fuel cell applications. One of Sandia's technology transfer partners is already producing the dendritic platinum foam-like nanospheres.

Major follow-up activities include providing further improvements in the preparation and properties of the novel catalysts and continued interaction with fuel cell companies to test the catalytic materials directly in working, state-of-the-art fuel cell formats and achieve real-time, real-world results to help plan further improvements and modifications of the materials.

Krista Edmonds reports from Sandia for Innovation.