AN ADVANCE at Argonne National Laboratory of the U.S. Department of Energy may significantly lower the cost of fuel cell propulsion. Briefly, Argonne researchers have developed a less costly replacement for platinum, the precious metal currently used as a catalyst in fuel cells (and also in traditional automotive catalytic converters).
An FCEV is an Electric Vehicle whose fuel cell stacks produce electricity by combining oxygen in the air with on-board hydrogen. That is, it’s an EV that makes its own E. No lengthy recharge times, no short ranges.
A catalyst encourages this electrochemical magic without actually taking part (sort of what I did back in Chem 101 and 102). With today’s technology, the platinum catalyst comprises about half the cost of a fuel cell stack, thus making it an extremely pricey item. (Imagine if pistons, for instance, cost half the price of a conventional engine.)
Catalytic action occurs at both the anode and cathode of a fuel cell. Hydrogen molecules are stripped of their electrons at the anode. The resulting electron flow has another name: “electricity.” The hydrogen protons that remain travel through a polymer electrolyte membrane to the cathode, where they react with the electrons and oxygen, thus forming water, the fuel cell’s only “emissions.”
The magic of a fuel cell producing electricity. Image from the Smithsonian National Museum of American History.
The Argonne development replaces all the platinum on the fuel cell’s cathode, which usually requires four times as much of this material as the anode. Also, enhanced design of both electrodes optimizes the flow of protons and electrons within the fuel cell and the removal of its water.
At left, conventional packing of catalyst; at right, Argonne’s nanofibrous catalyst. This and the following image from Argonne National Laboratory.
An optimized catalyst should be well distributed, both for best activity in encouraging the electrochemistry and also for channeling away the water that’s produced. Argonne researchers describe their work in “Highly Efficient Nonprecious Metal Catalyst Prepared with Metal-Organic Framework in a Continuous Carbon Nanofibrous Network,” published in the Proceedings of the National Academy of Sciences, August 25, 2015.
Nanofabrication of the non-precious-metal catalyst.
Nor is this merely theoretical. The researchers describe the nano-engineering involved in their catalyst production. It begins with electrospinning a polymer containing iron-based organometallics and metal-organic frameworks, all at the nano level. The result, researchers say, is a microporous network of nanofibers interconnected through a macroporous frame. The macro voids transport oxygen and water efficiently. The linked micro sites offer plenty of opportunity for catalytic activity.
I’m reminded of science writer/futurist Arthur C. Clarke’s line: “Any sufficiently advanced technology is indistinguishable from magic.”
All this, thanks to an interdisciplinary, international effort. The researchers, Jianglan Shui, Chen Chen, Lauren Grastanowicz, Dan Zhao and Di-Jia Liu, have affiliations with the Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois; the School of Materials Science and Engineering, Beihang University, Beijing, China; Alcoa Technical Center, New Kensington, Pennsylvania; and Department of Chemical and Biomolecular Engineering, National University of Singapore. ds
© Dennis Simanaitis, SimanaitisSays.com, 2015