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Producing Pure Hydrogen

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A major problem facing fuel cell technology is that the hydrogen-rich materials feeding the reaction often contain carbon monoxide (CO), which deteriorates the expensive platinum-based catalysts that convert hydrogen into electricity. Brookhaven researchers study catalysts that assist in eliminating these impurities through the “water-gas shift” (WGS) reaction, a process that combines CO with water to produce hydrogen gas and carbon dioxide. The ultimate goal is to find the catalysts that will help convert nearly 100 percent of the CO into carbon dioxide, an important step toward achieving a hydrogen-based economy.

Toward this effort, a group led by Brookhaven examined the nanoscale catalysts gold-cerium oxide and goldtitanium oxide. These catalysts usually consist of gold nanoparticles dispersed on a ceria or titania surface. But to get a better idea of how the catalysts work, the researchers studied the “inverse models,” ceria or titania nanoparticles on gold. Using powerful x-rays at Brookhaven’s National Synchrotron Light Source, in addition to scanning tunneling microscopy and calculations, the group found that although pure gold is inert for the WGS reaction, it becomes extremely active when combined with ceria or titanium. This high activity is due to the catalysts’ nanosized oxides, which are able to break apart water molecules – the most difficult part of the WGS reaction.

Publication

J.A. Rodriguez, S. Ma, P. Liu, J. Hrbek, J. Evans, and M. PĂ©rez, “Activity of CeOx and TiOx Nanoparticles Grown on Au(111) in the Water-Gas Shift Reaction,” Science, 318: 1757-1760 (2007).

Last Modified: November 04, 2009