Wet Method Grows Ultrathin Films | Chemical & Engineering News
Volume 93 Issue 47 | p. 26 | Concentrates
Issue Date: November 30, 2015

Wet Method Grows Ultrathin Films

Catalysis: Electrochemical technique provides atom-efficient route to making iridium catalysts
Department: Science & Technology
News Channels: Materials SCENE, Nano SCENE
Keywords: iridium, thin film, catalyst, deposition, water splitting
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This active electrocatalyst was grown via a wet-phase method that neatly deposited an atomically thin film of iridium on gold, as seen in this TEM image (gray) and corresponding X-ray elemental map (green and red).
Credit: Energy Environ. Sci.
Composite image of an alloy catalyst that includes an electron micrograph and an elemental map.
 
This active electrocatalyst was grown via a wet-phase method that neatly deposited an atomically thin film of iridium on gold, as seen in this TEM image (gray) and corresponding X-ray elemental map (green and red).
Credit: Energy Environ. Sci.

Researchers at the National Institute of Standards & Technology have developed a wet-phase analog of atomic layer deposition (ALD), a gas-phase thin-film growth method, and used it to prepare highly active iridium catalysts for water splitting (Energy Environ. Sci. 2015, DOI: 10.1039/c5ee02541a). ALD is touted for its ability to grow a predetermined number of atomic layers of a material only where the film is wanted, but the method requires costly, dedicated equipment. So NIST staff scientist Thomas P. Moffat and coworkers developed an inexpensive solution phase alternative. The team showed that its electrochemical layer-by-layer technique can be used to grow ultrathin films of iridium, a rare and expensive catalytic metal, by using an electrolyte solution containing K3IrCl6, Na2SO4, and H2SO4. The scientists grew films of iridium on gold, platinum, and nickel and evaluated them as catalysts for water splitting, a process that generates valuable hydrogen fuel. The team reports that the catalytic activity of its iridium films, just one monolayer thick, matches the top performing bulk polycrystalline iridium electrodes, demonstrating that the new deposition method provides a simple way to use this precious metal efficiently.

 
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ISSN 0009-2347
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