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Issue 17, 2015
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Coverage-dependent thermodynamic analysis of the formation of water and hydrogen peroxide on a platinum model catalyst

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Abstract

Understanding the selectivity of the oxygen reduction reaction, especially the formation of water versus hydrogen peroxide in fuel cells, is an ongoing challenge in electrochemistry, surface science and catalysis. In this study, we propose a comprehensive thermodynamic analysis of the reaction intermediates for the formation of water on Pt(111). Density functional theory calculations of all the elementary steps linking hydroxyl and hydroperoxyl surface species with water and hydrogen peroxide have been performed at low (1/12 ML, ML = monolayer) and high (1/4 ML) coverages. The reaction energy variation for the two competing elementary events (molecular oxygen dissociation and hydroperoxyl formation) is strongly coverage-dependent. For the direct dissociation, an increase is observed at low coverage with respect to the usual high coverage picture. The stability of the reaction intermediates is investigated from thermodynamic diagrams. At 353 K and a total pressure of 1 atm, water and hydroxyl surface species are expected to compete for adsorption on Pt(111).

Graphical abstract: Coverage-dependent thermodynamic analysis of the formation of water and hydrogen peroxide on a platinum model catalyst

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Publication details

The article was received on 21 Aug 2014, accepted on 10 Mar 2015 and first published on 18 Mar 2015


Article type: Paper
DOI: 10.1039/C4CP03755C
Citation: Phys. Chem. Chem. Phys., 2015,17, 11392-11400
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    Coverage-dependent thermodynamic analysis of the formation of water and hydrogen peroxide on a platinum model catalyst

    R. F. de Morais, A. A. Franco, P. Sautet and D. Loffreda, Phys. Chem. Chem. Phys., 2015, 17, 11392
    DOI: 10.1039/C4CP03755C

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