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Title: First-Principles Mechanistic Analysis of Dimethyl Ether Electro-Oxidation on Monometallic Single-Crystal Surfaces

Dimethyl ether is an attractive alternative to petroleum fuels due to its physical properties, comparable energy density to methanol and ethanol, and minimal deleterious environmental/toxicological effects. For direct fuel cells, it has a number of advantages over other prominent fuels, including easier storage with respect to hydrogen, lower toxicity and crossover when compared to methanol, and more facile complete oxidation as compared to ethanol (which includes a relatively difficult to break C–C bond). However, the dimethyl ether electro-oxidation reaction is poorly understood, hindering the development of improved electrocatalysts. Using periodic, self-consistent (PW91-GGA) density functional theory calculations, we evaluate the thermochemistry of dimethyl ether (DME) electro-oxidation, at the elementary step level, on 12 model, closed-packed facets of pure transition metals: Au, Ag, Cu, Pt, Pd, Ni, Ir, Rh, Co, Os, Ru, and Re. From the calculated thermochemistry, we determine the most probable reaction paths on each of these surfaces, focusing on Pt as a model system. Our results predict two key electro-oxidation peaks. At lower potentials, there is a peak corresponding to partial oxidation of DME to CO (and other surface poisoning species) or complete oxidation to CO 2 via formic acid as a key intermediate. A second, higher-potential peak ismore » due to complete oxidation of adsorbed CO (and other surface poisoning species) to CO 2. Assuming the catalysts remain in their metallic state during the DME electro-oxidation process, our results suggest that the onset potential of the surfaces increases in the order Cu < Ni < Os < Rh < Ir < Co < Ru < Pt < Ag < Pd < Re < Au. Using our results, we construct a theoretical phase diagram showing predicted catalyst activity based on two key reactivity descriptors, the free energies of adsorbed CO and OH. Here, we compare all results to methanol electro-oxidation to understand key mechanistic differences and their impacts on optimal catalyst design for direct DME fuel cells.« less
Authors:
 [1] ;  [1] ;  [1]
  1. Univ. of Wisconsin-Madison, Madison, WI (United States). Dept. of Chemical and Biological Engineering
Publication Date:
Grant/Contract Number:
FG02-05ER15731
Type:
Accepted Manuscript
Journal Name:
Journal of Physical Chemistry. C
Additional Journal Information:
Journal Volume: 118; Journal Issue: 42; Journal ID: ISSN 1932-7447
Publisher:
American Chemical Society
Research Org:
Univ. of Wisconsin-Madison, Madison, WI (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Contributing Orgs:
EMSL, a National scientific user facility at Pacific Northwest National Laboratory (PNNL); the Center for Nanoscale Materials at Argonne National Laboratory (ANL); and the National Energy Research Scientific Computing Center (NERSC)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; density functional theory; heterogeneous catalysis; thermochemistry; electrocatalysis; oxidation; dimethyl ether
OSTI Identifier:
1405315

Herron, Jeffrey A., Ferrin, Peter, and Mavrikakis, Manos. First-Principles Mechanistic Analysis of Dimethyl Ether Electro-Oxidation on Monometallic Single-Crystal Surfaces. United States: N. p., Web. doi:10.1021/jp505919x.
Herron, Jeffrey A., Ferrin, Peter, & Mavrikakis, Manos. First-Principles Mechanistic Analysis of Dimethyl Ether Electro-Oxidation on Monometallic Single-Crystal Surfaces. United States. doi:10.1021/jp505919x.
Herron, Jeffrey A., Ferrin, Peter, and Mavrikakis, Manos. 2014. "First-Principles Mechanistic Analysis of Dimethyl Ether Electro-Oxidation on Monometallic Single-Crystal Surfaces". United States. doi:10.1021/jp505919x. https://www.osti.gov/servlets/purl/1405315.
@article{osti_1405315,
title = {First-Principles Mechanistic Analysis of Dimethyl Ether Electro-Oxidation on Monometallic Single-Crystal Surfaces},
author = {Herron, Jeffrey A. and Ferrin, Peter and Mavrikakis, Manos},
abstractNote = {Dimethyl ether is an attractive alternative to petroleum fuels due to its physical properties, comparable energy density to methanol and ethanol, and minimal deleterious environmental/toxicological effects. For direct fuel cells, it has a number of advantages over other prominent fuels, including easier storage with respect to hydrogen, lower toxicity and crossover when compared to methanol, and more facile complete oxidation as compared to ethanol (which includes a relatively difficult to break C–C bond). However, the dimethyl ether electro-oxidation reaction is poorly understood, hindering the development of improved electrocatalysts. Using periodic, self-consistent (PW91-GGA) density functional theory calculations, we evaluate the thermochemistry of dimethyl ether (DME) electro-oxidation, at the elementary step level, on 12 model, closed-packed facets of pure transition metals: Au, Ag, Cu, Pt, Pd, Ni, Ir, Rh, Co, Os, Ru, and Re. From the calculated thermochemistry, we determine the most probable reaction paths on each of these surfaces, focusing on Pt as a model system. Our results predict two key electro-oxidation peaks. At lower potentials, there is a peak corresponding to partial oxidation of DME to CO (and other surface poisoning species) or complete oxidation to CO2 via formic acid as a key intermediate. A second, higher-potential peak is due to complete oxidation of adsorbed CO (and other surface poisoning species) to CO2. Assuming the catalysts remain in their metallic state during the DME electro-oxidation process, our results suggest that the onset potential of the surfaces increases in the order Cu < Ni < Os < Rh < Ir < Co < Ru < Pt < Ag < Pd < Re < Au. Using our results, we construct a theoretical phase diagram showing predicted catalyst activity based on two key reactivity descriptors, the free energies of adsorbed CO and OH. Here, we compare all results to methanol electro-oxidation to understand key mechanistic differences and their impacts on optimal catalyst design for direct DME fuel cells.},
doi = {10.1021/jp505919x},
journal = {Journal of Physical Chemistry. C},
number = 42,
volume = 118,
place = {United States},
year = {2014},
month = {8}
}