Crystal structure and surface characteristics of Sr-doped GdBaCo2O6−δ double perovskites: oxygen evolution reaction and conductivity. Issue 13 (4th December 2017)

• Record Type: Journal Article
• Authors: Pramana, Stevin S.; Cavallaro, Andrea; Li, Cheng; Handoko, Albertus D.; Chan, Kuang Wen; Walker, Robert J.; Regoutz, Anna; Herrin, Jason S.; Yeo, Boon Siang; Payne, David J.; Kilner, John A.; Ryan, Mary P.; Skinner, Stephen J.
• Is Part Of: Journal of materials chemistry. Volume 6:Issue 13(2018)
• Page Start: 5335
• Page End: 5345
• Publication Date: 2017-12-04
• Subjects: Materials -- Research -- Periodicals; Chemistry, Analytic -- Periodicals; Environmental sciences -- Research -- Periodicals; 543.0284
• DOI: 10.1039/c7ta06817d
• Languages: English
• ISSNs: 2050-7488

Abstract

Abstract : Upon Sr-doping in GdBa1− x Sr x Co2 O6− δ, a shift of the valence band maximum VBmax towards the Fermi energy E F was observed leading to better OER activity. 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 GdBa0.6 Sr0.4 Co2 O6− 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− x Sr x Co2 O6− δ with increasing Sr content was found to crystallise in the higher symmetry tetragonal P 4/ mmm space group in comparison with the undoped GdBaCo2 O6−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.