Ag Doping Modulating Cathode Acidic Sites to Enhance Chromium Resistance for Intermediate Temperature Solid Oxide Fuel Cells

doi:10.15541/jim20250105

Abstract

Abstract:

Cr poisoning is an important factor restricting the practical application of solid oxide fuel cell (SOFC) cathodes. In particular, the alkaline earth-rich perovskite oxide cathodes are prone to cation segregation and impurity poisoning at high temperatures, which can significantly reduce the cathode performance. To improve the Cr resistance of the cathode, the acid site of SrCo_0.9Ta_0.1O_3-_δ (SCT) was regulated by Ag doping, whose conductivity, catalytic activity, surface morphology, and composition were then systematically investigated. The results show that Ag doping enhances the conductivity of the material, and the doped material exhibits higher oxygen surface exchange coefficient, which is conducive to improving its cathodic catalytic activity. At 700 ℃, polarization resistance (R_p) of Sr_0.9Ag_0.1Co_0.9Ta_0.1O_3-_δ (SACT10) cathode is 0.0176 Ω·cm², significantly lower than that of SCT cathode (0.0366 Ω·cm²). In addition, due to the Ag doping strategy, the average valence state of Co in SACT10 material increases, which further increases the relative acidity and improves the Cr resistance. After operating in Cr-containing atmosphere for 22 h, R_p of SACT10 cathode is 0.205 Ω·cm², significantly lower than that of SCT cathode (0.964 Ω·cm²), and fewer inert secondary phases are observed on the surface of SACT10 cathode after testing. All above results confirm that Ag doping can effectively increase acid sites, improve activity and enhance Cr resistance. SACT10 obtained in this work is expected to be a promising medium temperature SOFC cathode material.

Key words: solid oxide fuel cell, chromium resistance, acidic site, alkaline earth cation, surface segregation

CLC Number:

TQ174

GAO Yuan, WEI Bo, JIN Fangjun, LÜ Zhe, LING Yihan. Ag Doping Modulating Cathode Acidic Sites to Enhance Chromium Resistance for Intermediate Temperature Solid Oxide Fuel Cells[J]. Journal of Inorganic Materials, 2026, 41(1): 70-78.

Figures/Tables 12

Fig. 1 (a) XRD patterns and (b) local enlargements of the as-prepared samples

Fig. 2 (a) Electrical conductivities of SCT, SACT5 and SACT10 samples in air and (b) their corresponding Arrhenius plots

Fig. 3 ECR curves at (a) 700, (b) 650 and (c) 600 ℃ of SCT, SACT5 and SACT10, and (d) their kchem

Fig. 4 EIS spectra of SCT, SACT5 and SACT10 cathodes at (a) 700 and (b) 650 ℃, and their (c) Rp and (d) corresponding Arrhenius plots Inset in (a): equivalent circuit

Fig. 5 (a-e) EIS spectra of different cathodes at 700 ℃ under Cr-containing atmosphere for different operating times; (f) DRT analysis of the corresponding EIS spectra of SACT10 cathode; (g) EIS spectra for different cathodes after operating, and (h) their corresponding DRT analysis (a) SCT; (b) S0.95CT; (c) S0.9CT; (d) SACT5; (e) SACT10

Fig. 6 SEM images of (a) SCT, (b) Cr-SCT, (c) Cr-S0.95CT, (d) Cr-S0.9CT, (e) Cr-SACT5, and (f) Cr-SACT10 dense pellets before and after treatment at 700 ℃ under Cr-containing atmosphere for 22 h

Fig. 7 SEM images of (a) SCT, (b) Cr-SCT, (c) Cr-SACT5, and (d) Cr-SACT10 cathodes before and after operating at 700 ℃ under Cr-containing atmosphere for 22 h

Fig. 8 XPS spectra of SACT10 before and after treatment under Cr-containing atmosphere at 700 ℃ (a) Sr3d; (b) Co2p; (c) O1s; (d) Cr2p; (e) Ag3d; (f) Ta4f. Colorful figures are available on website

Fig. S1 XRD patterns of precursor powders sintered at 880 ℃ for 5 h

Fig. S2 SEM-EDS elemental mappings of SACT10 pellet

Fig. S3 Raman spectra of samples treated in the Cr-containing atmosphere

Fig. S4 Particle size distributions of the secondary phases on the surface of dense pellets (a) Cr-SCT, (b) Cr-S0.95CT, (c) Cr-S0.9CT, (d) Cr-SACT5, and (e) Cr-SACT10 before and after treatment at 700 ℃ under Cr-containing atmosphere for 22 h

References 36

[1]	FU M, GAO Y, ZHANG M, et al. Vanadium-assisted surface engineering of heterostructured cathode for enhanced protonic ceramic fuel cell performance. Chemical Engineering Journal, 2025, 505: 159722. DOI URL
[2]	YE Z, ZOU G, WU Q, et al. Preparation and performances of tubular cone-shaped anode-supported segmented-in-series direct carbon solid oxide fuel cell. Journal of Inorganic Materials, 2024, 39(7): 819. DOI URL
[3]	ISHFAQ H A, KHAN M Z, SHIRKE Y M, et al. A heuristic approach to boost the performance and Cr poisoning tolerance of solid oxide fuel cell cathode by robust multi-doped ceria coating. Applied Catalysis B: Environmental, 2023, 323: 122178. DOI URL
[4]	GAO Y, HUANG X, WANG Z, et al. Cr deposition and poisoning on SrCo_0.9Ta_0.1O_3-_δ cathode of solid oxide fuel cells. International Journal of Hydrogen Energy, 2023, 48(6): 2341. DOI URL
[5]	ZHOU Y, LÜ Z, ZHANG R, et al. Mechanism of chromium poisoning on La_0.5Sr_0.5Co_0.25Fe_0.75O₃ cathode and enhancing chromium tolerance using a novel anion doping strategy. International Journal of Hydrogen Energy, 2024, 85: 114. DOI URL
[6]	ZHENG T, LI Z, WANG D, et al. Enhanced anti-chromium poisoning ability of high entropy La_0.2Nd_0.2Sm_0.2Sr_0.2Ba_0.2Co_0.2Fe_0.8O_3-_δ cathodes for solid oxide fuel cells. Journal of Alloys and Compounds, 2024, 982: 173753. DOI URL
[7]	HAO H, ZHANG Y, WANG Z, et al. Hydrogen spillover in superwetting Ni/NiMoN Mott-Schottky heterostructures for boosting ampere-level hydrogen evolution. Applied Physics Letters, 2025, 126: 113901. DOI URL
[8]	XIA B, ZHANG H, YAO C, et al. Enhancing ORR activity and CO₂ tolerance of Pr_0.4Sr_0.6Co_0.2Fe_0.8O_3-_δ-based SOFC cathode through synergistic doping and surface modification. Applied Surface Science, 2024, 649: 159143. DOI URL
[9]	BAI J, ZHOU D, NIU L, et al. Preparation of high-performance multiphase heterostructures IT-SOFC cathode materials by Pr-induced in situ assembly. Applied Catalysis B: Environment and Energy, 2024, 355: 124174. DOI URL
[10]	ZHANG X, LIU B, YANG Y, et al. Advances in component and operation optimization of solid oxide electrolysis cell. Chinese Chemical Letters, 2023, 34(5): 108035. DOI
[11]	LI J, HOU J, LU Y, et al. Ca-containing Ba_0.95Ca_0.05Co_0.4Fe_0.4Zr_0.1Y_0.1O_3-_δ cathode with high CO₂-poisoning tolerance for proton-conducting solid oxide fuel cells. Journal of Power Sources, 2020, 453: 227909. DOI URL
[12]	CHEN Z, MA B, DANG C, et al. Entropy engineering strategies for optimizing solid oxide cell air electrode performance: a review. Journal of Alloys and Compounds, 2025, 1010: 177585. DOI URL
[13]	ZHANG X, JIN Y, JIANG Y, et al. Enhancing chromium poisoning tolerance of La_0.8Sr_0.2Co_0.2Fe_0.8O_3-_δ cathode by Ce_0.8Gd_0.2O_1.9-_δ coating. Journal of Power Sources, 2022, 547: 231996. DOI URL
[14]	YUAN M, WANG Z, GAO J, et al. Turning bad into good: a medium-entropy double perovskite oxide with beneficial surface reconstruction for active and robust cathode of solid oxide fuel cells. Journal of Colloid and Interface Science, 2024, 672: 787. DOI PMID
[15]	SHEN L, DU Z, ZHANG Y, et al. Medium-entropy perovskites Sr(Fe_αTi_βCo_γMn_ζ)O_3-_δ as promising cathodes for intermediate temperature solid oxide fuel cell. Applied Catalysis B: Environmental, 2021, 295: 120264. DOI URL
[16]	GAO Y, LING Y, WANG X, et al. Sr-deficient medium-entropy Sr_1-_xCo_0.5Fe_0.2Ti_0.1Ta_0.1Nb_0.1O_3-_δ cathodes with high Cr tolerance for solid oxide fuel cells. Chemical Engineering Journal, 2024, 479: 147665. DOI URL
[17]	GAO L, LI Q, SUN L, et al. A novel family of Nb-doped Bi_0.5Sr_0.5FeO_3-_δ perovskite as cathode material for intermediate- temperature solid oxide fuel cells. Journal of Power Sources, 2017, 371: 86. DOI URL
[18]	GAO Y, HUANG X, YUAN M, et al. A SrCo_0.9Ta_0.1O_3-_δ derived medium-entropy cathode with superior CO₂ poisoning tolerance for solid oxide fuel cells. Journal of Power Sources, 2022, 540: 231661. DOI URL
[19]	CHEN Z P, JIN F J, LI M F, et al. Double perovskite Sr₂CoFeO₅₊_δ: preparation and performance as cathode material for intermediate- temperature solid oxide fuel cells. Journal of Inorganic Materials, 2024, 39(3): 337. DOI URL
[20]	KIM D, PARK J W, YUN B, et al. Correlation of time-dependent oxygen surface exchange kinetics with surface chemistry of La_0.6Sr_0.4Co_0.2Fe_0.8O_3-_δ catalysts. ACS Applied Materials & Interfaces, 2019, 11(35): 31786.
[21]	CHEN D, CHEN C, BAIYEE Z M, et al. Nonstoichiometric oxides as low-cost and highly-efficient oxygen reduction/evolution catalysts for low-temperature electrochemical devices. Chemical Reviews, 2015, 115(18): 9869. DOI PMID
[22]	LIU X, ZHANG L, ZHENG Y, et al. Uncovering the effect of lattice strain and oxygen deficiency on electrocatalytic activity of perovskite cobaltite thin films. Advanced Science, 2019, 6(6): 1801898. DOI URL
[23]	XU C, SUN W, REN R, et al. A highly active and carbon-tolerant anode decorated with in situ grown cobalt nano-catalyst for intermediate-temperature solid oxide fuel cells. Applied Catalysis B: Environmental, 2021, 282: 119553. DOI URL
[24]	YAO C, YANG J, ZHANG H, et al. Evaluation of A-site Ba-deficient PrBa_0.5-_xSr_0.5Co₂O₅₊_δ (x = 0, 0.04 and 0.08) as cathode materials for solid oxide fuel cells. Journal of Alloys and Compounds, 2021, 883: 160759. DOI URL
[25]	WANG G, ZHANG Y, HAN M. Densification of Ce_0.9Gd_0.1O_2-_δ interlayer to improve the stability of La_0.6Sr_0.4Co_0.2Fe_0.8O_3-_δ/ Ce_0.9Gd_0.1O_2-_δ interface and SOFC. Journal of Electroanalytical Chemistry, 2020, 857: 113591. DOI URL
[26]	WANG R, SUN Z, LU Y, et al. Comparison of chromium poisoning between lanthanum strontium manganite and lanthanum strontium ferrite composite cathodes in solid oxide fuel cells. Journal of Power Sources, 2020, 476: 228743. DOI URL
[27]	JIN F, LIU X, CHU X, et al. Effect of nonequivalent substitution of Pr^3+/4+ with Ca²⁺ in PrBaCoFeO₅₊_δ as cathodes for IT-SOFC. Journal of Materials Science, 2021, 56(2): 1147. DOI
[28]	YUAN M, WANG Z, GAO J, et al. Configuration entropy tailored beneficial surface segregation on double perovskite cathode with enhanced Cr-tolerance for SOFC. Ceramics International, 2024, 50(9): 15076. DOI URL
[29]	XIONG C, QIU P, ZHANG W, et al. Influence of practical operating temperature on the Cr poisoning for LSCF-GDC cathode. Ceramics International, 2022, 48(22): 33999. DOI URL
[30]	GAO M, KONYSHEVA E Y, YANG J. Tailoring kinetics of Cr-chemisorption over La_0.6Sr_0.4Fe_0.8Co_0.2O₃ cathode material through its porosity variation. International Journal of Hydrogen Energy, 2022, 47(97): 41336. DOI URL
[31]	PAN Y, XU X, ZHONG Y, et al. Direct evidence of boosted oxygen evolution over perovskite by enhanced lattice oxygen participation. Nature Communications, 2020, 11: 2002. DOI PMID
[32]	ZHAO Y, DONGFANG N, HUANG C, et al. Operando monitoring of the functional role of tetrahedral cobalt centers for the oxygen evolution reaction. Nature Communications, 2025, 16: 580. DOI
[33]	JEONG N C, LEE J S, TAE E L, et al. Acidity scale for metal oxides and Sanderson's electronegativities of lanthanide elements. Angewandte Chemie International Edition, 2008, 47(52): 10128. DOI URL
[34]	NICOLLET C, TOPARLI C, HARRINGTON G F, et al. Acidity of surface-infiltrated binary oxides as a sensitive descriptor of oxygen exchange kinetics in mixed conducting oxides. Nature Catalysis, 2020, 3(11): 913. DOI
[35]	XIAOKAITI P, YU T, YOSHIDA A, et al. Effects of cobalt and iron proportions in Pr_0.4Sr_0.6Co_0.9-_xFe_xNb_0.1O_3-_δ electrode material for symmetric solid oxide fuel cells. Journal of Alloys and Compounds, 2020, 831: 154738. DOI URL
[36]	ZHANG W, ZHANG L, GUAN K, et al. Effective promotion of oxygen reduction activity by rare earth doping in simple perovskite cathodes for intermediate-temperature solid oxide fuel cells. Journal of Power Sources, 2020, 446: 227360. DOI URL