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Issue 16, 2012
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Theoretical analysis of the conversion mechanism of acetylene to ethylidyne on Pt(111)

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Abstract

The conversion of acetylene to ethylidyne on Pt(111) has been comprehensively investigated using self-consistent periodic density functional theory. Geometries and energies for all of the intermediates involved as well as the conversion mechanism were analyzed. On Pt(111), the carbon atoms in the majority of stable C2Hx (x = 1–4) intermediates prefer saturated sp3 configurations with the missing H atoms substituted by the adjacent metal atoms. The most favorable conversion pathway for acetylene to ethylidyne is via a three-step reaction mechanism, acetylenevinyl → vinylidene → ethylidyne. The first step, acetylenevinyl, depends on the availability of surface H atoms: without preadsorbed H the reaction occurs via the initial disproportionation of acetylene, which resulted in adsorbed vinyl; with an abundance of preadsorbed H, acetylene could transform to vinyl via both the disproportionation and hydrogenation reactions. Conversions through initial dehydrogenation of acetylene and isomerizations of acetylene and vinyl are unfavorable due to high energy barriers along the relevant pathways. The conversion rate involving vinylidene as an intermediate is at least 100 times larger than that involving ethylidene.

Graphical abstract: Theoretical analysis of the conversion mechanism of acetylene to ethylidyne on Pt(111)

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Publication details

The article was received on 16 Jan 2012, accepted on 17 Feb 2012 and first published on 17 Feb 2012


Article type: Paper
DOI: 10.1039/C2CP40149E
Citation: Phys. Chem. Chem. Phys., 2012,14, 5642-5650
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    Theoretical analysis of the conversion mechanism of acetylene to ethylidyne on Pt(111)

    X. Lu, L. Liu, Y. Li, W. Guo, L. Zhao and H. Shan, Phys. Chem. Chem. Phys., 2012, 14, 5642
    DOI: 10.1039/C2CP40149E

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