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Finding optimal surface sites on heterogeneous catalysts by counting nearest neighbors

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Science  09 Oct 2015:
Vol. 350, Issue 6257, pp. 185-189
DOI: 10.1126/science.aab3501

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Accounting for surface coordination

The exploration of heterogeneous catalysts using first-principles calculations can be daunting because the large number of atoms and possible surface geometries. Calle-Vallejo et al. describe a simpler metric for assessing optimal reactivity: a weighted average of surface coordination that includes second-nearest neighbors (see the Perspective by Stephens et al.). The calculations identified three approaches for introducing cavity sites into the platinum(111) surface to improve its performance for the oxygen reduction reaction used in fuel cells.

Science, this issue p. 185, see also p. 164

Abstract

A good heterogeneous catalyst for a given chemical reaction very often has only one specific type of surface site that is catalytically active. Widespread methodologies such as Sabatier-type activity plots determine optimal adsorption energies to maximize catalytic activity, but these are difficult to use as guidelines to devise new catalysts. We introduce “coordination-activity plots” that predict the geometric structure of optimal active sites. The method is illustrated on the oxygen reduction reaction catalyzed by platinum. Sites with the same number of first-nearest neighbors as (111) terraces but with an increased number of second-nearest neighbors are predicted to have superior catalytic activity. We used this rationale to create highly active sites on platinum (111), without alloying and using three different affordable experimental methods.

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