Role of Pr-Vacancies and O-Interstitials on the Activity and Stability of (Pr1−xLnx)2NiO4 (Ln = La, Nd, Pm, Sm, Gd, Tb, Dy, and Ho) towards Oxygen Reduction Reactions: A DFT Study
Journal Article
·
· Journal of the Electrochemical Society
- Henan Normal University (China); University of Louisiana at Lafayette, LA (United States); OSTI
- Henan Normal University (China)
- University of Louisiana at Lafayette, LA (United States)
- Peking University, Beijing (China)
Praseodymium nickelate, Pr2NiO4 (PNO), is a promising electrode to promote oxygen reduction reaction (ORR) in a solid oxide fuel cell, but it exhibits phase transformation during electrochemical operation. The origin of the simultaneous phase transformation and high electrochemical performance remains obscure. We carried out a systematic density functional theory study to elucidate the mechanism for this conjugated phenomenon. Charge, electronic structure, and normal-mode analysis suggest the presence of peroxide. Our study shows that the formation of peroxide (O22–) is attributed to both oxygen interstitials and Pr vacancies. The peroxide species limits the oxygen ion migration due to the additional energy required to break its O–O bond, which leads to a decrease in ORR activity. Subsequently, we investigate the diffusion paths of Pr-ions while comparing them with those of other Ln3+ ions (La, Nd, Pm, Sm, Gd, Tb, Dy, and Ho) in PNO. The formation energies for various Ln3+ cation occupancies are calculated, as well as segregation energies in CeO2(111) surfaces. Lastly, criteria for effective Ln3+ dopants are developed. La, Nd, and Pm are proposed as potential substituents in PNO to obtain a stable structure.
- Research Organization:
- University of South Carolina, Columbia, SC (United States)
- Sponsoring Organization:
- USDOE Office of Fossil Energy (FE)
- Grant/Contract Number:
- FE0026097
- OSTI ID:
- 1980863
- Journal Information:
- Journal of the Electrochemical Society, Journal Name: Journal of the Electrochemical Society Journal Issue: 12 Vol. 168; ISSN 0013-4651
- Publisher:
- IOP PublishingCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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