A shift in chemistry moves fuel cells closer to reality

Two scientists at Brown University, chemistry professor Shouheng Sun and graduate student Vismadeb Mazumder, and Miaofang Chi and Karren More at the Oak Ridge Laboratory have discovered an alternative to the most expensive part of fuel cells, the pure-platinum catalyst.  The researchers created a nanoparticle that uses less platinum while lasting longer. 

During the last decade fuel cells were touted by the Bush administration as the answer to sustainable, eco-friendly transportation.  Fuel cells would power our vehicles while producing nothing but pure water.  Unfortunately the technology did not live up to the hype until researchers at Brown University and Oak Ridge National Laboratory created “a nanoparticle with a palladium core and an iron-platinum shell.”

The nanoparticle consists of “a five-nanometer palladium (Pd) core… encircled…with a shell consisting of iron and platinum (FePt).”  The researchers accomplished this by “by decomposing iron pentacarbonyl [Fe(CO)₅] and reducing platinum acetylacetonate [Pt(acac)₂].”  They expect to be able to produce a shell that will contain even less platinum further cutting costs. 

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 cathode 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 Journal of the American Chemical Society.

The new nanoparticle out performs pure platinum as a cathode and lasts longer.  Experiments showed that the new “palladium/iron-platinum nanoparticles generated 12 times more current than commercially available pure-platinum catalysts” and could last ten times longer.  They also found that a one nanometer shell worked better than a three nanometer shell also reducing costs.

Although the palladium core improves the cathode performance of fuel cells, the scientists want to use “a more chemically active metal” to see if an even greater improvement can be accomplished.  After they settle on a core whether it be palladium or some other metal, they will still need to scale the nanoparticles up for commercial use.

This breakthrough moves fuel cells one step closer as a viable competitor to electric cars and another alternative to fossil fuel powered vehicles. 

One step closer to reality but with a long distance left to go.

Photo credit: Vismadeb Mazumder & Shouheng Sun, Brown University

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