advances.sciencemag.org/cgi/content/full/4/6/eaap9360/dc1 Supplementary Materials for Oxygen-deficient triple perovskites as highly active and durable bifunctional electrocatalysts for oxygen electrode reactions Nam-In Kim, Young Jin Sa, Tae Sup Yoo, Sung Ryul Choi, Rana Arslan Afzal, Taekjib Choi, Young-Soo Seo, Kug-Seung Lee, Jun Yeon Hwang, Woo Seok Choi, Sang Hoon Joo, Jun-Young Park This PDF file includes: Published 15 June 2018, Sci. Adv. 4, eaap9360 (2018) DOI: 10.1126/sciadv.aap9360 fig. S1. Structural and elemental analyses of the perovskite catalysts. fig. S2. Nitrogen adsorption-desorption and XPS analysis of the perovskite catalysts. fig. S3. ORR activity of the perovskite catalysts. fig. S4. Structural changes of the perovskite catalysts after or during the OER. fig. S5. Physicochemical and electrochemical characterizations of the NBCFM/NrGO catalyst. fig. S6. Long-term durability and stability of catalysts for OER and ORR. fig. S7. EIS analysis of the perovskite-based catalysts. fig. S8. Optical properties and electronic structures of the perovskite-based catalysts. table S1. Textural properties of the perovskite-based catalysts. table S2. Comparison of the OER/ORR bifunctional activity of NBCFM/N-rGO with the reported bifunctional perovskite catalysts.
fig. S1. Structural and elemental analyses of the perovskite catalysts. (A C) SEM images of BSCF, NBSCF, and NBCFM. (D F) TEM images of BSCF, NBSCF, and NBCFM. (G) low magnification (scale bar: 200 nm) and (H) high magnification (scale bar: 20 nm) EDX elemental mapping images. (I) Composition of each element in NBCFM catalyst as atomic ratio from the EDX analysis.
fig. S2. Nitrogen adsorption-desorption and XPS analysis of the perovskite catalysts. (A) Nitrogen adsorption-desorption isotherms and (B) corresponding pore size distributions of BSCF, NBSCF, and NBCFM. XPS spectra of the perovskite-based catalysts: (C) Co 2p, (D) Fe 2p, and (E) Mn 2p.
j 1 (cm 2 ma 1 ) j 1 (cm 2 ma 1 ) j 1 (cm 2 ma 1 ) j (ma cm 2 ) j (ma cm 2 ) j (ma cm 2 ) A D 0-1 -2-3 -4-5 -6-7 0.8 0.6 400 rpm 900 rpm 1600 rpm 2500 rpm -8 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 0.40 V 0.45 V 0.50 V 0.55 V 0.60 V 0.65 V n = 2.8 B E 0-1 -2-3 -4-5 -6-7 0.8 0.6 NBSCF (Double) 400 rpm 900 rpm 1600 rpm 2500 rpm -8 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 0.40 V 0.45 V 0.50 V 0.55 V 0.60 V 0.65 V NBSCF (Double) n = 3.6 C F 0-1 -2-3 -4-5 -6-7 0.8 0.6 400 rpm 900 rpm 1600 rpm 2500 rpm -8 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 0.40 V 0.45 V 0.50 V 0.55 V 0.60 V 0.65 V n = 3.9 0.4 0.4 0.4 0.2 0.2 0.2 G 0.01 0.02 0.03 0.04 0.05 0.06 ω 1/2 (rpm 1/2 ) 0.90 H 0.90 0.01 0.02 0.03 0.04 0.05 0.06 ω 1/2 (rpm 1/2 ) I 0.90 0.01 0.02 0.03 0.04 0.05 0.06 ω 1/2 (rpm 1/2 ) 0.85 0.80 64 mv dec 1 0.85 0.80 87 mv dec 1 0.85 0.80 63 mv dec 1 0.75 0.75 0.75 0.70 0.65-2.0-1.5-1.0-0.5 0.0 0.5 Log (j k / ma cm 2 ) 0.70 NBSCF (Double) 0.65-2.0-1.5-1.0-0.5 0.0 0.5 Log (j k / ma cm 2 ) 0.70 0.65-2.0-1.5-1.0-0.5 0.0 0.5 Log (j k / ma cm 2 ) fig. S3. ORR activity of the perovskite catalysts. (A C) ORR polarization curves at different rotation speeds, (D F) Koutecky-Levich plots, and (G I) Tafel plots determined at 1,600 rpm.
fig. S4. Structural changes of the perovskite catalysts after or during the OER. (A C) TEM images after OER durability tests for BSCF, NBSCF, and NBCFM. (D F) In situ Co K-edge XANES spectra of BSCF, NBSCF, and NBCFM.
fig. S5. Physicochemical and electrochemical characterizations of the NBCFM/N-rGO catalyst. (A) TEM image of NBCFM/N-rGO. (B) XRD patterns of NBCFM and NBCFM/N-rGO. (C) N 2 adsorption-desorption isotherm of NBCFM/N-rGO and corresponding pore size distributions (inset). XPS spectra for NBCFM/N-rGO: (D) survey spectrum, (E) N 1s (left) and C 1s (right), and (F) Co 2p., (G) Raman spectra of GO, N-rGO, and NBCFM/N-rGO. and (H) Koutecky-Levich plots of NBCFM/N-rGO for the ORR.
j (ma cm 2 ) j (ma cm 2 ) A 30 25 20 15 10 5 12 11 10 9 8 NBCFM/N-rGO Ir/C 1.56 1.60 1.64 B Overpotential (V) 0.8 0.7 0.6 0.5 0.4 NBCFM/N-rGO NBSCF (Double) Ir/C C 0 0-1 -2-3 -4-5 -6 1.3 1.4 1.5 1.6 1.7 NBCFM/N-rGO Pt/C D Overpotential (V) 0.3 0.9 0.8 0.7 0.6 0.5 0.4 0 2 4 6 8 10 Time (h) NBCFM/N-rGO NBSCF (Double) Pt/C -7 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 E 5 nm 0.3 F Normailzed Absorption 0 2 4 6 8 10 Time (h) NBCFM/N-rGO As-deposited 1.55 V 7720 7722 7710 7720 7730 7740 7750 7760 Photon Energy (ev) fig. S6. Long-term durability and stability of catalysts for OER and ORR. (A) OER polarization curves of BSCF, NBCFM, NBCFM/N-rGO, and Ir/C before (solid line) and after (dotted line) the potential cycling. (B) OER stabilities of BSCF, NBSCF, NBCFM, NBCFM/NrGO, and Ir/C measured by chronopotentiometry at 5 ma cm 2 for 10 h. (C) ORR polarization curves of BSCF, NBCFM, NBCFM/N-rGO, and Pt/C before (solid line) and after (dotted line) the potential cycling. (D) ORR stabilities of BSCF, NBSCF, NBCFM, NBCFM/N-rGO, and Pt/C measured by chronopotentiometry at 3 ma cm 2 for 10 h. (E) TEM image of NBCFM/N-rGO after durability test. (F) In situ Co K-edge XANES spectrum of NBCFM/N-rGO.
fig. S7. EIS analysis of the perovskite-based catalysts. (A) Nyquist plots and (B) calculated charge transport resistance (R ct ) of catalysts. (C) Nyquist plots and (D) calculated R ct of NBCFM/N-rGO under applied current density (5, 7, and 10 ma cm 2 ).
fig. S8. Optical properties and electronic structures of the perovskite-based catalysts. Room temperature (A) real (ε 1 (ω)) and (B) imaginary (ε 2 (ω)) parts of the dielectric function obtained from spectroscopic ellipsometry. (C) Simplified electronic structures of the perovskite-based catalysts. Real part of the optical conductivity spectra σ 1 (ω) is shown for (D) BSCF, (E) NBSCF, and (F) NBCFM. The symbols correspond to the experimentally measure spectra, while the black line corresponds to the fitting of the spectra using different Lorentz oscillators (lines with different colors). table S1. Textural properties of the perovskite-based catalysts. Catalyst BSCF (Single perovskite) NBSCF (Double perovskite) NBCFM (Triple perovskite) BET surface area (m 2 g 1 ) Total pore volume (cm 3 g 1 ) 12.3 0.017 7.7 4.6 0.011 13.6 7.1 0.022 16.0 Mean pore diameter (nm) NBCFM/N-rGO 119.6 0.345 6.2
table S2. Comparison of the OER/ORR bifunctional activity of NBCFM/N-rGO with the reported bifunctional perovskite catalysts. All the catalysts were tested in 0.1 M KOH, except for Nd 0.5 Sr 0.5 CoO 3 δ /IC (Ref. 34), which was tested in 0.1 M LiOH. Catalyst Oxide Loading (μg cm 2 ) Carbon Type NBCFM/N-rGO 418 N-doped rgo Carbon Loading (μg cm 2 ) E OER E ORR Ref. (V) 209 0.70 This work La 0.5 Sr 0.5 CoO 2.91 68 Vulcan 390 1.09 6 Core-corona LaNiO 3 /NCNT 1220 a 0.96 7 nslanio 3 /NC 51 N-doped C N/A 1.02 8 La 0.3 (Ba 0.5 Sr 0.5 ) 0.7 Co 0.8 Fe 0.2 O 3 δ 639 Ketjen Black 159 1 9 La 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3 /NRGO 410 a 0.92 10 LaTi 0.65 Fe 0.35 O 3 δ /NC N/A N-doped C N/A 1.05 11 La 0.58 Sr 0.4 Fe 0.4 Co 0.6 O 3 /NCNT 210 a 0.83 20 La 0.8 Sr 0.2 Mn 0.6 Ni 0.4 O 3 140 Vulcan 28 1.28 21 La 0.95 FeO 3 δ 232 Super P 232 1.26 27 La 0.7 (Ba 0.5 Sr 0.5 ) 0.3 Co 0.8 Fe 0.2 O 3 δ 639 Ketjen Black 159 1.01 28 LaNiO 3 δ 720 Super C65 144 1.04 29 LaNi 0.8 Fe 0.2 O 3 40 Vulcan 180 1.1 30 La 0.5 Sr 0.5 CoO 3 δ 230 Ketjen Black 50 1.04 31 LaNiO 3 /NCNT 1220 a 0.94 32 La(Co 0.55 Fe 0.45 ) 0.99 O 3 δ /NrGO 250 a 0.96 33 Nd 0.5 Sr 0.5 CoO 3 δ /IC 210 a 1.02 34 CaMnO 3 85 Vulcan 200 1.08 35 a The catalysts are the chemical hybrids between perovskite and carbon. For the other cases, the carbon additives were physically mixed with the perovskite catalysts to enhance electrical conductivity.