N.E. Chemcat Corporation licenses Brookhaven Lab electrocatalyst technology for fuel cells in electric vehicles
3 January 2012
Japan-based N.E. Chemcat Corporation, a leading catalyst and precious metal compound manufacturer, has licensed electrocatalysts developed by scientists at the US Department of Energy’s Brookhaven National Laboratory (BNL) that can reduce the use of costly platinum and increase the effectiveness of fuel cells for use in electric vehicles. In addition, the license includes innovative methods for making the catalysts and an apparatus design used in manufacturing them.
The electrocatalysts consist of a palladium or a palladium alloy nanoparticle core covered with a monolayer—one-atom thick—platinum shell. (Earlier post.) This palladium-platinum combination notably improves oxygen reduction at the cathode of a hydrogen/oxygen fuel cell.
N.E. Chemcat currently provides highly active carbon supported platinum catalysts and alloy catalysts for fuel cell cathode applications, and carbon supported Pt-Ru catalysts and Pt-Ru black catalysts for anode applications.
Platinum is the most efficient electrocatalyst for fuel cells, but platinum-based catalysts are expensive, unstable, and have low durability. The newly licensed electrocatalysts have high activity, stability, and durability, while containing only about one tenth the platinum of conventional catalysts used in fuel cells, reducing overall costs.
In a paper published late last year in the journal Angewandte Chemie, International Edition, the BNL researchers reported that the new monolayer electrocatalyst maintained high levels of reactivity during tests that mimic stop-and-go driving—a critical challenge for fuel cells.
With conventional platinum fuel-cell catalysts, the oxidation and reduction cycling—triggered by changes in voltage that occur during stop-and-go driving—damages the platinum. Over time, the platinum dissolves, causing irreversible damage to the fuel cell.
With the new catalyst, palladium from the core is more reactive than platinum in these oxidation and reduction reactions. Stability tests simulating fuel cell voltage cycling revealed that after 100,000 potential cycles, a significant amount of palladium had been oxidized, dissolved, and migrated away from the cathode. In the membrane between the cathode and anode, the dissolved palladium ions were reduced by hydrogen diffusing from the anode to form a “band,” or dots.
In contrast, platinum was almost unaffected, except for a small contraction of the platinum monolayer. Reactivity of the platinum monolayer/palladium core catalyst also remained extremely high. It was reduced by merely 37% after 100,000 cycles.
The US Department of Energy’s Office of Science and its Office of Energy Efficiency and Renewable Energy funded research that contributed to these licensed technologies. Additional funding came from the Toyota Motor Corporation. Besides Adzic, those who contributed to the research include Brookhaven chemists Jia Wang, Kotaro Sasaki, and Miomir Vukmirovic, and postdoctoral fellows Junliang Zhang and Yibo Mo.
Sasaki, K., Naohara, H., Cai, Y., Choi, Y. M., Liu, P., Vukmirovic, M. B., Wang, J. X. and Adzic, R. R. (2010), Core-Protected Platinum Monolayer Shell High-Stability Electrocatalysts for Fuel-Cell Cathodes. Angewandte Chemie International Edition, 49: 8602–8607. doi: 10.1002/anie.201004287
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