Crystal structure and surface characteristics of Sr-doped GdBaCo2O6−δ double perovskites: oxygen evolution reaction and conductivity

Stevin S. Pramana, Andrea Cavallaro, Cheng Li, Albertus D. Handoko, Kuang Wen Chan, Robert J. Walker, Anna Regoutz, Jason S. Herrin, Boon Siang Yeo, David J. Payne, John A. Kilner, Mary P. Ryan, Stephen J. Skinner

    Research output: Contribution to journalArticlepeer-review

    21 Scopus citations

    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 GdBa0.6Sr0.4Co2O6−δ 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). GdBa1−xSrxCo2O6−δ with increasing Sr content was found to crystallise in the higher symmetry tetragonal P4/mmm space group in comparison with the undoped GdBaCo2O6−δ 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.
    Original languageEnglish (US)
    Pages (from-to)5335-5345
    Number of pages11
    JournalJournal of Materials Chemistry A
    Volume6
    Issue number13
    DOIs
    StatePublished - 2018

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