{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,23]],"date-time":"2026-10-23T21:05:52Z","timestamp":1792789552285,"version":"4.5.0"},"reference-count":24,"publisher":"MDPI AG","issue":"19","license":[{"start":{"date-parts":[[2026,10,7]],"date-time":"2026-10-07T00:00:00Z","timestamp":1791331200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2026,10,7]],"date-time":"2026-10-07T00:00:00Z","timestamp":1791331200000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Ministry of Science and Higher Education of the Republic of Kazakhstan","award":["AP26103025"],"award-info":[{"award-number":["AP26103025"]}],"id":[{"id":"https:\/\/ror.org\/05tyne317","id-type":"ROR","asserted-by":"crossref"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Materials"],"abstract":"<jats:p>Cobalt-free SrFeO3\u2212\u03b4 is an attractive mixed ionic-electronic conducting (MIEC) oxygen-electrode platform for intermediate-temperature solid oxide fuel cells (IT-SOFCs), but its electrochemical response is strongly coupled to Fe valence, oxygen non-stoichiometry, and structural phase stability. Here, B-site Ce-substituted SrFe1\u2212xCexO3\u2212\u03b4 (x = 0, 0.05, 0.10, 0.15, and 0.20) was prepared by a solid-state route to establish a composition-structure-defect-transport relationship. X-ray diffraction and Rietveld refinement show an initial expansion of the perovskite lattice after Ce introduction, followed by a lattice-parameter plateau and weak CeO2\/Sr3Fe2O7\u2212\u03b4 segregation at higher Ce contents. Electron microscopy confirms an interconnected granular morphology, while HRTEM\/SAED of SrFe0.85Ce0.15O3\u2212\u03b4 verifies well-crystallized perovskite domains. XPS reveals a Ce-dependent redistribution of the Fe3+\/Fe4+ and surface oxygen environments, with the x = 0.15 composition displaying the most favorable defect-associated oxygen response. Electrical conductivity follows a non-monotonic composition dependence and is maximized at x = 0.15, indicating an optimum balance between defect formation and continuity of the Fe-O-Fe transport network. A single cell employing SrFe0.85Ce0.15O3\u2212\u03b4 as the oxygen electrode delivers a peak power density of 0.53 W cm\u22122 at 800 \u00b0C. The corresponding polarization resistance decreases from 0.47 \u03a9 at 600 \u00b0C to 0.36 \u03a9 at 800 \u00b0C, confirming strongly activated oxygen-electrode kinetics. These results identify controlled B-site Ce substitution as an effective route for tuning the electronic\/defect chemistry of cobalt-free SrFeO3\u2212\u03b4 cathodes.<\/jats:p>","DOI":"10.3390\/ma19194245","type":"journal-article","created":{"date-parts":[[2026,10,7]],"date-time":"2026-10-07T10:13:02Z","timestamp":1791367982000},"page":"4245","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["High-Performance Cobalt-Free SrFe1\u2212xCexO3\u2212\u03b4 Cathode Enabled by Ce-Driven Defect Engineering for IT-SOFCs"],"prefix":"10.3390","volume":"19","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-6336-9524","authenticated-orcid":false,"given":"Packiaraj","family":"Rajagopal","sequence":"first","affiliation":[{"name":"Institute of Physical and Technical Sciences, L.N. Gumilyov Eurasian National University, Astana 010008, Kazakhstan"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"conceptualization","vocabulary":"credit"},{"role":"methodology","vocabulary":"credit"},{"role":"investigation","vocabulary":"credit"},{"role":"data-curation","vocabulary":"credit"},{"role":"writing-original-draft","vocabulary":"credit"}]},{"given":"Mahitha","family":"Rajasekaran","sequence":"additional","affiliation":[{"name":"Department of Physics, School of Advanced Sciences, Kalasalingam Academy of Research and Education, Virudhunagar 626126, India"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"investigation","vocabulary":"credit"},{"role":"data-curation","vocabulary":"credit"},{"role":"validation","vocabulary":"credit"},{"role":"formal-analysis","vocabulary":"credit"}]},{"given":"Sivaganesh","family":"Dhanushkodi","sequence":"additional","affiliation":[{"name":"Research Group for Advanced Materials and Sustainable Catalysis, State Key Laboratory Breeding Base of Green Chemistry-Synthesis Technology, College of Chemical Engineering, Zhejiang University of Technology, Hangzhou 310032, China"},{"name":"Anhui International Exchange and Cooperation Base, Qing Yang Institute for Industrial Minerals, Qingyang 242804, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"writing-original-draft","vocabulary":"credit"},{"role":"conceptualization","vocabulary":"credit"}]},{"given":"Ainur","family":"Aimakhanova","sequence":"additional","affiliation":[{"name":"Institute of Physical and Technical Sciences, L.N. Gumilyov Eurasian National University, Astana 010008, Kazakhstan"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"investigation","vocabulary":"credit"},{"role":"validation","vocabulary":"credit"},{"role":"data-curation","vocabulary":"credit"},{"role":"methodology","vocabulary":"credit"}]},{"given":"Mukhammed","family":"Kenzhebek","sequence":"additional","affiliation":[{"name":"Institute of Physical and Technical Sciences, L.N. Gumilyov Eurasian National University, Astana 010008, Kazakhstan"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"investigation","vocabulary":"credit"},{"role":"validation","vocabulary":"credit"}]},{"given":"Aliya","family":"Baratova","sequence":"additional","affiliation":[{"name":"Institute of Physical and Technical Sciences, L.N. 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Gumilyov Eurasian National University, Astana 010008, Kazakhstan"},{"name":"Faculty of Integrated Technologies, Universiti Brunei Darussalam, Gadong BE1410, Brunei"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"conceptualization","vocabulary":"credit"},{"role":"writing-review-editing","vocabulary":"credit"},{"role":"resources","vocabulary":"credit"}]},{"given":"Asset","family":"Kabyshev","sequence":"additional","affiliation":[{"name":"Institute of Physical and Technical Sciences, L.N. 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