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Crystal structure and surface characteristics of Sr-doped GdBaCo₂O_6-d double perovskites: oxygen evolution reaction and conductivity

Lookup NU author(s): Dr Stevin PramanaORCiD

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

Abstract

A cheap and direct solution towards engineering better catalysts through identification of novel materials is required for a sustainable energy system. Perovskite oxides have emerged as potential candidates to replace the less economically attractive Pt and IrO₂ water splitting catalysts. In this work, excellent electrical conductivity (980 S cm^-1 ) was found for the double perovskite of composition GdBa_0.6Sr_0.4Co₂O_6-d which is consistent with a better oxygen evolution reaction activity with the onset polarisation of 1.51 V with respect to a reversible hydrogen electrode (RHE). GdBa_1-xSr_xCo₂O_6-d with increasing Sr content was found to crystallise in the higher symmetry tetragonal P4/mmm space group in comparison with the undoped GdBaCo₂O_6-d which is orthorhombic (Pmmm), and yields higher oxygen uptake, accompanied by higher Co oxidation states. This outstanding electrochemical performance is explained by the wider carrier bandwidth, which is a function of Co–O–Co buckling angles and Co–O bond lengths. Furthermore the higher oxygen evolution activity was observed despite the formation of non-lattice oxides (mainly hydroxide species) and enrichment of alkaline earth ions on the surface.

Publication metadata

Author(s): Pramana SS, Cavallaro A, Li C, Handoko AD, Chan KW, Walker RJ, Regoutz A, Herrin JS, Yeo BS, Payne DJ, Kilner JA, Ryan MP, Skinner SJ

Publication type: Article

Publication status: Published

Journal: Journal of Materials Chemistry A

Year: 2018

Volume: 6

Issue: 13

Pages: 5335-5345

Print publication date: 07/04/2018

Online publication date: 04/12/2018

Acceptance date: 20/10/2017

Date deposited: 22/01/2018

ISSN (print): 2050-7488

ISSN (electronic): 2050-7496

Publisher: Royal Society of Chemistry

URL: https://doi.org/10.1039/C7TA06817D

DOI: 10.1039/C7TA06817D

Data Access Statement: http://dx.doi.org/10.17634/154300-55

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