Chemistry

Electrifying Peroxide Synthesis

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Science  09 Dec 2011:
Vol. 334, Issue 6061, pp. 1325
DOI: 10.1126/science.334.6061.1325-b
CREDIT: ALAMY.COM

Traditionally, the purpose of a fuel cell has been to channel chemical energy into electrical energy, and research has focused on optimizing the design to maximize the efficiency of this transformation. In this context, reducing oxygen all the way to water, rather than stopping halfway at hydrogen peroxide, is a central feature. On the other hand, there's a market for hydrogen peroxide, and the current production route is frustratingly indirect (featuring the intermediacy of an organic quinone compound). Jirkovsky et al. consider the prospect of using polymer electrolyte fuel cells to cogenerate electricity and hydrogen peroxide. Beginning with the knowledge that certain gold surfaces manifest relatively high selectivity toward the partial reduction reaction, they performed density functional theory calculations to guide optimization. The calculations suggested that isolated Pd or Pt sites on the gold surface should enhance O2 binding while suppressing scission of the O-O bond, but that adjacent centers of the second metal would promote further reduction to water. These predictions were then borne out in rotating ring-disc electrode measurements: Peroxide selectivity peaked near 95% at a Pd alloying concentration of 8%, but then plummeted as the Pd abundance passed 15% (the threshold for aggregation).

J. Am. Chem. Soc. 133, 10.1021/ja206477z (2011).

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