Effect of b site coordination environment in the ORR activity in disordered brownmillerites Ba2In2-xCexO5+delta

TitleEffect of b site coordination environment in the ORR activity in disordered brownmillerites Ba2In2-xCexO5+delta
Publication TypeJournal Article
Year of Publication2015
AuthorsJijil, CP, Bhange, SN, Kurungot, S, R. Devi, N
JournalACS Applied Materials & Interfaces
Volume7
Issue5
Pagination3041-3049
Date PublishedFEB
ISSN1944-8244
Keywordsbrownmillerite, fuel cell, oxygen disorder, oxygen reduction reaction, Rietveld refinement
Abstract

Ba2In2O5 brownmillerites in which the In site is progressively doped with Ce exhibit excellent oxygen reduction activity under alkaline conditions. Ce doping leads to structural changes advantageous for the reaction. Twenty-five percent doping retains the ordered structure of brownmillerite with alternate layers of tetrahedra and octahedra, whereas further increase in Ce concentration creates disorder. Structures with disordered oxygen atoms/vacancies are found to be better oxygen reduction reaction catalysts probably aided by isotropic ionic conduction, and Ba2In0.5Ce1.5O5+delta is the most active. This enhanced activity is correlated to the more symmetric Ce site coordination environment in this compound. Stoichiometric perovskite BaCeO3 with the highest concentration of Ce shows very poor activity emphasizing the importance of oxygen vacancies, which facilitate O-2 adsorption, in tandem with catalytic sites in oxygen reduction reactions.

DOI10.1021/am5087837
Type of Journal (Indian or Foreign)

Foreign

Impact Factor (IF)

7.145

Divison category: 
Catalysis and Inorganic Chemistry
Physical and Materials Chemistry