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Why Ni is absent from the surface of La2NiO4+δ?

Lookup NU author(s): Dr Stevin PramanaORCiD



This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


© The Royal Society of Chemistry.La2NiO4+δ (LNO214) is a potential intermediate temperature solid oxide fuel cell (IT-SOFC) cathode material which belongs to the Ruddlesden-Popper (RP) structure series An+1BnO3n+1. There is interest in this material as it offers a way to avoid Sr segregation and associated degradation, as LNO214 can take in oxygen interstitials and become catalytically active without A-site doping. While the bulk ionic conduction mechanisms are well studied, its surface structure and chemistry are still a matter of debate. Recent experimental studies (both with and without dopants) reveal that it has a La-terminated surface and a highly Ni deficient surface layer. These results disagree with previous computer simulations, and undermine the conventional explanation for the oxygen reduction process at the surface. In this work we evaluate the thermodynamic stability of La2NiO4+δ at IT-SOFC operation temperatures. We find that the decomposition of La2NiO4+δ to produce La2O3 and higher order RP phases is indeed thermodynamically favourable. A hypothesis for the formation mechanism of the La-terminated and Ni deficient surface based on partial decomposition and surface passivation is proposed and evaluated.

Publication metadata

Author(s): Wu J, Pramana SS, Skinner SJ, Kilner JA, Horsfield AP

Publication type: Article

Publication status: Published

Journal: Journal of Materials Chemistry A

Year: 2015

Volume: 3

Issue: 47

Pages: 23760-23767

Print publication date: 21/12/2015

Online publication date: 16/10/2015

Acceptance date: 13/10/2015

Date deposited: 06/04/2017

ISSN (print): 2050-7488

ISSN (electronic): 2050-7496

Publisher: Royal Society of Chemistry


DOI: 10.1039/c5ta03759j


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