Cost is a crucial to making fuel-cell-powered vehicles a commercially viable technology. Over the past decade, engineers have made significant progress in shrinking the price tag for these systems, but there is still room for improvement before fuel cells are a competitive alternative to gasoline engines or battery-driven motors.
A big chunk of a fuel cell's price tag comes from the materials, namely precious metals like platinum. In a fuel cell's anode, the metal strips electrons off hydrogen gas, and in the cathode, it reduces oxygen to water. An average fuel-cell-powered car needs about 30 grams of platinum, which costs upward of $4,000.
Current designs cost 80 percent less and use one-fifth the platinum of their predecessors a decade ago (ClimateWire, June 4). Nonetheless, when it comes to expensive materials, scientists are still working to do more with less, or even none at all.
Some recent research highlights different strategies to this end. In a paper published earlier this week in the journal Nature Materials, scientists in Germany outlined an approach to increase platinum's effective surface area. Since the catalytic process occurs only at the metal's surface, expanding its surface area means it can carry out more reactions at the same time.
Scientists created a platinum alloy blended with nickel, forming three-dimensional shapes at the nanometer scale -- in this case, octahedrons. The shape of these tiny particles increased the catalyst's surface area dramatically, and the recipe used 10 percent of the platinum needed for conventional designs.
The zero platinum approach
Another research team including the University of North Texas, Case Western Reserve University and the Ulsan National Institute of Science and Technology in South Korea investigated ways to move electrons without using any metals at all, outlining their findings earlier this month in Scientific Reports.
Liming Dai, a co-author, and Kent Hale Smith, professor at Case Western Reserve, explained that the team started with a carbon material, graphene, and processed it using a technique called ball milling, forming graphene nanoplatelets. The researchers blended other molecules, like iodine and chlorine, into the particles as well to tweak their properties.
The material proved more stable than platinum and is more resistant to contamination and poisoning from other molecules like carbon monoxide. One formula for these particles produced 33 percent more current in cathode than a commercial platinum catalyst.
Though the technique requires some extra work, the raw material is cheap and production ramps up easily. "So overall, the cost for larger-scale production of the doped graphene for fuel cell applications is still much cheaper than platinum," Dai said.
Researchers are concentrating on using these platelets as a cathode material since that is where the bulk of the platinum in a fuel cell is used, but Dai said the approach could apply to anodes as well. Scientists are also working on making these materials more acid-resistant so they can work with other fuel cell chemistries.
Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC. www.eenews.net, 202-628-6500