(58e) Dimethyl Ether Electro-Oxidation on Platinum Surfaces

Dimethyl Ether Electro-Oxidation on Platinum Surfaces

Luke T. Roling, Jeffrey A. Herron, Winny Budiman, Peter Ferrin, and Manos Mavrikakis
Dimethyl ether (DME) has attracted significant interest as an alternative fuel, particularly in direct low- temperature fuel cell applications.1 Pt catalysts have demonstrated good activity for DME electro- oxidation, but require a high overpotential due to poisoning by CO. This motivates a deeper understanding of the reaction mechanism for the design of improved catalysts. This reaction demonstrates substantial structure sensitivity, which has been studied experimentally on Pt(111)2, Pt(100)3, and stepped4 Pt surfaces. Of these, Pt(100) demonstrates the highest DME electro-oxidation activity. Using periodic, self-consistent density functional theory (DFT), we perform a detailed evaluation of DME electro-oxidation kinetics and thermodynamics on Pt(100), Pt(111), and Pt(211) surfaces. We
use these data to postulate probable reaction mechanisms on each surface as a function of overpotential. By comparing these mechanisms and key elementary steps involved in electro-oxidation, we uncover the origin of the observed structure sensitivity of DME electro-oxidation on Pt surfaces.
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