Theoretical Investigation of H₂ Oxidation on the Sr₂Fe_1.5Mo_0.5O6 (001) Perovskite Surface under Anodic Solid Oxide Fuel Cell Conditions

Author(s)

Suwit Suthirakun, University of South Carolina - Columbia
Salai Cheettu Ammal, University of South Carolina - Columbia
Ana B. Muñoz-García, University of Naples Federico II
Guoliang Xiao, University of South Carolina - Columbia
Fanglin Chen, University of South Carolina - ColumbiaFollow
Hans-Conrad zur Loye, University of South Carolina - ColumbiaFollow
Emily A. Carter, Princeton University
Andreas Heyden, University of South Carolina - ColumbiaFollow

Document Type

Paper

Subject Area(s)

Chemistry

Abstract

Periodic density functional theory (DFT) calculations and microkinetic modeling are used to investigate the electrochemical oxidation of H₂ fuel on the (001) surface of Sr₂Fe_1.5Mo_0.5O₆(SFMO) perovskite under anodic solid oxide fuel cell conditions. Three surface models with different Fe/Mo ratios in the topmost layer−identified by ab initio thermodynamic analysis−are used to investigate the H₂ oxidation mechanism. A microkinetic analysis that considers the effects of anode bias potential suggests that a higher Mo concentration in the surface increases the activity of the surface toward H₂ oxidation. At operating voltage and anodic SOFC conditions, the model predicts that water desorption is rate-controlling and that stabilizing the oxygen vacancy structure increases the overall rate for H₂ oxidation. Although we find that Mo plays a crucial role in improving catalytic activity of SFMO, under fuel cell operating conditions, the Mo content in the surface layer tends to be very low. On the basis of these results and in agreement with previous experimental observations, a strategy for improving the overall electrochemical performance of SFMO is increasing the Mo content or adding small amounts of an active transition metal, such as Ni, to the surface to lower the oxygen vacancy formation energy of the SFMO surface.

Digital Object Identifier (DOI)

https://doi.org/10.1021/ja502629j

Publication Info

Published in Journal of the American Chemical Society, Volume 136, Issue 23, 2014, pages 8374-8386.

Rights

© Journal of the American Chemical Society 2014, American Chemical Society.

APA Citation

Suthirakun, S., Ammal, S., Muñoz-García, A., Xiao, G., Chen, F., zur Loye, H.-C., Carter, E., & Heyden, A. (2014). Theoretical Investigation of H2 Oxidation on the Sr2Fe1.5Mo0.5O6 (001) Perovskite Surface under Anodic Solid Oxide Fuel Cell Conditions. Journal of the American Chemical Society, 136(23), 8374–8386. https://doi.org/10.1021/ja502629j