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Categories: advanced materials, energy

BSA 08-27: Underpotential Mediated Layer-by-Layer Metal Deposition

BNL Reference Number: BSA 08-27

Patent Status: PCT filed on June 23, 2009

Summary

Increase in catalytic activity for the oxygen reduction reaction (ORR) after coating palladium-on-carbon catalysts with four monolayers of platinum by underpotential deposition.

Platinum is a very good, albeit expensive, electrocatalyst. In order to increase the catalytic activity of an electrocatalyst per mass of noble metal (the mass activity), nanoparticles of less expensive materials are coated with atomically thin layers of platinum. First a monolayer of a sacrificial base metal such as copper or lead is deposited onto a core particle via underpotential deposition. Then the base metal is replaced by galvanic displacement with the catalytically active more noble metal. The coated composite can be used as an electrocatalyst in place of pure platinum, for example, in fuel cells.

Description

This invention utilizes copper underpotential deposition (UPD) potential cycles to enhance the interlayer diffusion rate during a diffusion-controlled overpotential deposition of platinum on palladium nanoparticles, for example. The deposition starts at the potential near Cu bulk deposition where a full monolayer Cu covers the Pd surface. As the Cu monolayer is partially stripped in the positive potential sweep, Pt is deposited under diffusion control. When the potential sweep turns in negative direction, Cu UPD covers the deposited Pt preventing multiplayer growth before the completion of the first Pt layer.

Journal Publication

• Overpotential deposition of Ag monolayer and bilayer on Au(1 1 1) mediated by Pb adlayer (.pdf)

Have Questions?

For more information about this technology, contact Kimberley Elcess, (631) 344-4151.