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

a Department of Materials, Imperial College London, Exhibition Road, London, SW7 2AZ, United Kingdom. b. School of Engineering, Newcastle University, Newcastle upon Tyne, NE1 7RU, United Kingdom. c Department of Chemistry, Faculty of Science, National University of Singapore, 3 Science Drive 3, Singapore 117543. d Agency for Science, Technology and Research (A*STAR), Institute of Materials Research and Engineering, Innovis Building, 2 Fusionopolis Way, Singapore 138634. e Facility for Analysis, Characterization, Testing and Simulation, Nanyang Technological University, Nanyang Avenue, Singapore 639798. f International Institute for Carbon Neutral Energy Research (WPI-I2CNER), Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan.


Figure S2 :
Figure S2: Rietveld plot of the XRD data of GB9S1CO collected at room temperature (R wp = 0.029, R Bragg = 0.009).The observed and calculated intensity are shown by blue and red line, respectively, with the differences plotted beneath.Vertical markers indicate the Bragg reflections.

Figure S3 :
Figure S3: Rietveld plot of the XRD data of GB8S2CO collected at room temperature with the 200 and 020 region enlarged as an inset to justify the Pmmm space group rather than P4/mmm (R wp = 0.028, R Bragg = 0.005).The observed and calculated intensity are shown by blue and red line, respectively, with the differences plotted beneath.Vertical markers indicate the Bragg reflections of 99.1(2) wt.% GB8S2CO (top) and 0.9(2) wt.% GdCoO 3 (bottom) phases.

Figure S5 :
Figure S5: Rietveld plot of the XRD data of GB6S4CO collected at room temperature with the 200 region enlarged as an inset to justify the P4/mmm space group (R wp = 0.025, R Bragg = 0.005).The observed and calculated intensity are shown by blue and red line, respectively, with the differences plotted beneath.Vertical markers indicate the Bragg reflections of 97.6(3) wt.% GB6S4CO (top) and 2.4(3) wt.% GdCoO 3 (bottom) phases.

Figure S7 :
Figure S7: (a) Axial and equatorial bond lengths of Co-O and (b) equatorial buckling angle of Co-O-Co and bandwidth w.

Table S8 : Co-O bond lengths, bond valence sums and Co oxidation state determined from titration for GB8S2CO and GB7S3CO. <Co1-O> means the average of bond length of Co1 polyhedron.
R 0 values used for the bond valence summations Co 3+ -O = 1.70