Fig. 1 XRD patterns of (a) LSF, LSFNCMT and LaFeO3 (PDF#75-0439) samples; (b) Local zoom of main peaks

Fig. 2 XRD patterns of mixture of electrolyte materials YSZ with LSF (a) and LSFNCMT (b) and GDC with LSF (c) and LSFNCMT (d)

Fig. 3 Electrochemical performance of symmetric cell under different temperatures in air (a) EIS spectra of LSFNCMT electrode; (b) EIS spectra of LSF and LSFNCMT electrodes at 800 ℃; (c) Rp and (d) corresponding Arrhenius plots of two symmetric cells

Fig. 4 Electrochemical performance of symmetrical cell under different p(O2) at 700 ℃ (a, b) EIS spectra (a) and DRT curves (b) of LSFNCMT; (c) DRT curves of LSF and LSFNCMT under p(O2) of 2.1×104 Pa at 700 ℃; (d) Dependence of each Rp as a function of p(O2) for LSFNCMT. Colorful figures are available on website

Fig. 5 EIS spectra (a) and variation of Rp (b) of LSFNCMT symmetric cell within 22 h in Cr vapor at -200 mA·cm-2 and 700 ℃

Fig. 6 Electrochemical performance of the single cell at 650-800 ℃ in wet H2 (3% (in volume) H2O) (a) I-V and power density curves of LSFNCMT cathodes; (b) I-V and power density curves of LSF and LSFNCMT cathodes at 800 ℃; (c) OCV and (d) MPD varied with temperature of different single cells

Fig. 7 Electrochemical performance of the anode-supported single cell at 650-800 ℃ in wet H2 (3% (in volume) H2O) (a) EIS spectra of LSFNCMT cathode; (b) EIS spectra of LSF and LSFNCMT cathodes at 800 ℃; (c) Rp at different temperatures and (d) corresponding Arrhenius plots of different single cells

Fig. 8 Cross-sectional SEM image of single cell with LSFNCMT cathode

Fig. S1 SEM image (a) and corresponding EDS element mappings (b) of LSFNCMT

Fig. S2 EIS spectra of symmetric cell with LSF electrode in air at different temperatures

Fig. S3 EIS spectra of symmetric cell with LSF electrode under different p(O2) at 700 ℃

Fig. S4 EIS spectra (a) and variation of Rp (b) of symmetric cell with LSF electrode within 22 h in Cr vapor at -200 mA·cm-2 and 700 ℃

Fig. S5 I-V and power density curves of single cell with LSF cathode at 650-800 ℃ with wet H2 (3% (in volume) H2O)

Fig. S6 EIS spectra of single cell with LSF cathode at 650-800 ℃ with wet H2 (3% (in volume) H2O)

Fig. S7 Cross-sectional SEM images of symmetric cells with LSF (a) and LSFNCMT (b) electrodes

Fig. S8 Cross-sectional SEM image of single cell with LSF cathode