Chemistry

Put On a Platinum Face

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Science  08 May 2009:
Vol. 324, Issue 5928, pp. 693
DOI: 10.1126/science.324_693c

Precious metals such as platinum are widely used in industrial catalysts. One way to reduce the amount of precious metal used—and hence the cost of the catalyst—is to create core-shell particles in which a core consisting of a cheaper, nonprecious metal is surrounded by a precious-metal shell. Methods for creating such particles, such as high-temperature treatment and chemical leaching, commonly lead to the loss of active surface area as a result of reduced particle sizes. Mayrhofer et al. report a method in which carbon monoxide (CO) adsorption causes surface segregation of platinum in a platinum-cobalt catalyst. The authors explored both gas-phase and electrochemical treatments, both of which lead to particles with an alloy core and a platinum shell, as evidenced by cyclic voltammetry and CO stripping measurements. The modified catalysts have higher activity than the untreated system in the oxygen reduction reaction. Particle sizes remain unaltered, without the loss of active surface area.

Angew. Chem. Int. Ed.48, 3529 (2009).

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