TY - JOUR
T1 - Oxygen reduction and transport on the La1-xSrxCo 1-yFeyO3-δ cathode in solid oxide fuel cells
T2 - A first-principles study
AU - Wang, Zhenbin
AU - Peng, Ranran
AU - Zhang, Wenhua
AU - Wu, Xiaojun
AU - Xia, Changrong
AU - Lu, Yalin
N1 - Publication details (e.g. title, author(s), publication statuses and dates) are captured on an “AS IS” and “AS AVAILABLE” basis at the time of record harvesting from the data source. Suggestions for further amendments or supplementary information can be sent to [email protected].
PY - 2013/11/7
Y1 - 2013/11/7
N2 - Oxygen reduction and successive migration on a cathode are key steps in solid oxide fuel cells. In this work, we have systematically studied the adsorption, dissociation, incorporation, and successive diffusion of oxygen species on the La1-xSrxCo1-yFe yO3 (LSCF) cathode on the basis of density-functional theory calculation. We found that the O2 molecule prefers to be adsorbed on the transition metal atoms at the B site (Fe or Co) than those at the A site (La or Sr). The oxygen molecule forms either superoxide (O 2-) or peroxide (O22-) species on the surface transition metal atoms, and the isomerisation energy barrier energies between them are less than 0.14 eV. The SrCo-terminated surface has the smallest oxygen vacancy formation energy, and the existence of surface oxygen vacancy promotes the oxygen dissociation on the B-site atom without an energy barrier. Instead, without the surface oxygen vacancy, the oxygen dissociation on the Co site needs to overcome an energy barrier of 0.30 eV, while that on the Fe site is about 0.14 eV. The calculated minimum energy pathways indicate that the energy barrier of oxygen migration on the surface is much higher than that in the bulk which contains the oxygen vacancy. Moreover, increasing the concentration of Co will effectively facilitate the formation of oxygen vacancy, greatly enhancing the oxygen bulk transport. Our study presents a comprehensive understanding of the mechanism of oxygen reduction and migration on the LSCF cathode. © 2013 The Royal Society of Chemistry.
AB - Oxygen reduction and successive migration on a cathode are key steps in solid oxide fuel cells. In this work, we have systematically studied the adsorption, dissociation, incorporation, and successive diffusion of oxygen species on the La1-xSrxCo1-yFe yO3 (LSCF) cathode on the basis of density-functional theory calculation. We found that the O2 molecule prefers to be adsorbed on the transition metal atoms at the B site (Fe or Co) than those at the A site (La or Sr). The oxygen molecule forms either superoxide (O 2-) or peroxide (O22-) species on the surface transition metal atoms, and the isomerisation energy barrier energies between them are less than 0.14 eV. The SrCo-terminated surface has the smallest oxygen vacancy formation energy, and the existence of surface oxygen vacancy promotes the oxygen dissociation on the B-site atom without an energy barrier. Instead, without the surface oxygen vacancy, the oxygen dissociation on the Co site needs to overcome an energy barrier of 0.30 eV, while that on the Fe site is about 0.14 eV. The calculated minimum energy pathways indicate that the energy barrier of oxygen migration on the surface is much higher than that in the bulk which contains the oxygen vacancy. Moreover, increasing the concentration of Co will effectively facilitate the formation of oxygen vacancy, greatly enhancing the oxygen bulk transport. Our study presents a comprehensive understanding of the mechanism of oxygen reduction and migration on the LSCF cathode. © 2013 The Royal Society of Chemistry.
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U2 - 10.1039/c3ta11554b
DO - 10.1039/c3ta11554b
M3 - RGC 21 - Publication in refereed journal
SN - 2050-7488
VL - 1
SP - 12932
EP - 12940
JO - Journal of Materials Chemistry A
JF - Journal of Materials Chemistry A
IS - 41
ER -
