Highlights Structural evolution of Sr2FeMo0.6Ni0.4O6 (SFNM) is studied in various reduction conditions. XRD and TPR characterizations provides insights into the redox behavior of SFMN. Metals exsolution and the formation of a Ruddlesden-Popper (RP) are interdependent phenomena. Cathodic polarization causes metal nanoparticles to be covered by the RP phase. This unusual morphology increases the CO2 electroreduction activity into SOEC.
