Title: Dimethyl ether electro-oxidation on platinum surfaces

Abstract

A first-principles density functional theory study was performed in this paper to elucidate the mechanism of dimethyl ether electro-oxidation on three low-index platinum surfaces (Pt(111), Pt(100), and Pt(211)). The goal of this study is to provide a fundamental explanation for the high activity observed experimentally on Pt(100) compared to Pt(111) and stepped surfaces. We determine that the enhanced activity of Pt(100) stems from more facile C–O bond breaking kinetics, as well as from easier removal of CO as a surface poison through activation of water. In general, the C–O bond (in CH_xOCH_y) becomes easier to break as dimethyl ether is dehydrogenated to a greater extent. In contrast, dehydrogenation becomes more difficult as more hydrogen atoms are removed. We perform two analyses of probable reaction pathways, which both identify CHOC and CO as the key reaction intermediates on these Pt surfaces. We show that the reaction mechanism on each surface is dependent on the cell operating potential, as increasing the potential facilitates C–H bond scission, in turn promoting the formation of intermediates for which C–O scission is more facile. We additionally demonstrate that CO oxidation determines the high overpotential required for electro-oxidation on Pt surfaces. Finally, at practical operating potentials (~0.60more » V_RHE), we determine that C–O bond breaking is most likely the most difficult step on all three Pt surfaces studied.« less

Authors:

Roling, Luke T. ^[1]; Herron, Jeffrey A. ^[1]; Budiman, Winny ^[1]; Ferrin, Peter ^[1]; Mavrikakis, Manos ^[1]

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+ Show Author Affiliations

1. Univ. of Wisconsin, Madison, WI (United States)

Publication Date:

Sat Feb 27 00:00:00 EST 2016

Research Org.:

Univ. of Wisconsin, Madison, WI (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES); USDOE Office of Science (SC), Biological and Environmental Research (BER)

OSTI Identifier:

1395848

Alternate Identifier(s):

OSTI ID: 1397344

Grant/Contract Number:  

FG02-05ER15731; AC02-06CH11357; AC02-05CH11231

Resource Type:

Accepted Manuscript

Journal Name:

Nano Energy

Additional Journal Information:

Journal Volume: 29; Journal ID: ISSN 2211-2855

Publisher:

Elsevier

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; dimethyl ether; transition metals; fuel cell; structure sensitivity; density functional theory