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First-Principles Modeling of Ni_4M (M = Co, Fe, and Mn) Alloys as Solid Oxide Fuel Cell Anode Catalyst for Methane Reforming

Tsai, Ho-Cheng and Morozov, Sergey I. and Yu, Ted H. and Merinov, Boris V. and Goddard, William A., III (2016) First-Principles Modeling of Ni_4M (M = Co, Fe, and Mn) Alloys as Solid Oxide Fuel Cell Anode Catalyst for Methane Reforming. Journal of Physical Chemistry C, 120 (1). pp. 207-214. ISSN 1932-7447. http://resolver.caltech.edu/CaltechAUTHORS:20160105-110644565

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Abstract

In this study, we used quantum mechanics (QM) to investigate steam reforming of methane on Ni-alloy catalyst surfaces and to examine the effect of anode material modifications on the catalytic processes in a solid oxide fuel cell (SOFC). The conventional Ni anode suffers from coking, coarsening, and sulfur poisoning because of the decomposition of hydrocarbon fuels, Ni particle agglomeration at high operating temperature, and impurities contained in fuels. Ni-electrode surface modification, such as alloying Ni with other metals (e.g., Fe and Cu), is probably the most practical and promising way of developing SOFC anodes tolerant to coking and sulfur poisoning. According to experimental data, Ni_4Fe shows a good catalytic performance and excellent long-term stability as an SOFC anode catalyst. We have performed QM calculations of segregation energy for various surface structures of five-layer Ni_4M slabs (M = Co, Fe, and Mn) and found that Ni atoms show segregation preference for the surface layer and the most favorable Ni_4M surface structure has two M atoms in the 2nd layer and one M atom in the 3rd and in the 4th layer (the numbering starts from the bottom layer). This structure was used for our further QM calculations of binding energies for CH_x, C, and H. We find that the Ni_4M(111) surfaces bind CH_x species weaker (by 1–10 kcal/mol) than pure Ni, and the binding energy of C is always ∼10 kcal/mol lower for the Ni_4M alloys compared to pure Ni. This is consistent with improved catalytic characteristics of certain Ni-based alloys compared to pure Ni obtained in experiment. Reaction energy barriers for methane decomposition on the Ni_4M(111) catalyst surfaces were calculated as well. On the basis of these results, the rate-determining step for the methane decomposition was found to be the CH → C + H reaction. Our results predict that Ni_4Fe and Ni_4Mn have both better activity and better coking resistance and can be considered as candidates for an SOFC anode catalyst suitable for the CH_4 fuel reforming.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1021/acs.jpcc.5b06847DOIArticle
http://pubs.acs.org/doi/full/10.1021/acs.jpcc.5b06847PublisherArticle
http://pubs.acs.org/doi/suppl/10.1021/acs.jpcc.5b06847Related ItemSupporting Information
ORCID:
AuthorORCID
Goddard, William A., III0000-0003-0097-5716
Additional Information:© 2015 American Chemical Society. Received: July 15, 2015. Revised: December 7, 2015. This work was partially supported by SAMSUNG under the Global Research Outreach (GRO) Program (grant SAMS.FC). The facilities of the Materials and Process Simulation Center used in this study were established with grant N00014-12-1-0818 from DURIP-ONR. T. H. Y. was partially funded by the CSULB start up grant and faculty reassigned time. The authors declare no competing financial interest.
Funders:
Funding AgencyGrant Number
SAMSUNG/Global Research Outreach (GRO) ProgramSAMS.FC
Office of Naval Research (ONR)N00014-12-1- 0818
Cal State Long BeachUNSPECIFIED
Record Number:CaltechAUTHORS:20160105-110644565
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20160105-110644565
Official Citation:First-Principles Modeling of Ni4M (M = Co, Fe, and Mn) Alloys as Solid Oxide Fuel Cell Anode Catalyst for Methane Reforming Ho-Cheng Tsai, Sergey I. Morozov, Ted H. Yu, Boris V. Merinov, and William A. Goddard, III The Journal of Physical Chemistry C 2016 120 (1), 207-214 DOI: 10.1021/acs.jpcc.5b06847
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:63377
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:05 Jan 2016 19:49
Last Modified:18 Feb 2016 22:20

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