Nanosized Fe-doped ceria samples synthesized by freeze-drying precursor method

M. MAZAN; JAASIEL MARRERO-JEREZ; S.A. LARRONDO.; PEDRO NÚÑEZ

Sevilla

Congreso; EHEC 2014 ?European Hydrogen Energy Conference?; 2014

Solid-oxide fuel cells (SOFCs) are promising candidates for stationary power generation due to the possibility of using syngas obtained from fossil fuels or biogas. Nowadays, the investigations are concern about the reduction of the operating temperature to the intermediate temperature range(500-700°C) in order to make this technology economically feasible. Reducing the operatingtemperature reduces the kinetics of the processes that occur at the interfaces gas/electrodeincreasing the associated polarization resistance. In this context, the use of nanomaterials is entirelyfeasible. These materials have special properties associated with the greatest contribution of thesurface where it is possible to accommodate large number of defects, which can be beneficialincreasing the electrochemical performance, either lowering the polarization resistance of the anodeor by providing new active sites conferring resistance to coke formation, sulfur poisoning, etc.Many materials have been tested as anodes with different structures (spinels, pyrochlore,perovskite, etc.). However, CeO2-based materials with fluorite structure appear to be the mostpromising because the resistance to coke formation, their ability to oxidize the carbon that may beformed in reactions with hydrocarbons [1-4]. Despite the good characteristics mentioned, thesematerials have poor electronic conductivity and mechanical stability. Doping with aliovalent cationswith higher ionic radius, like Gd3+ and with isovalent cations with lower ionic radius, like Zr4+, hasbeen intensively studied. Therefore, it is interesting to study the effect of doping with an aliovalentcation like Fe3+, with a lower ionic radius, on the physicochemical properties with the objective todevelop ceria-based materials with structural and redox properties appropriated for electrocatalyticapplication.In this work the synthesis of nanosized Ce1-xFexO2-freeze-drying precursor method, as a potential electrode material for IT-SOFCs, is presented. The soobtainedsolids were characterized by Scanning Electron Microscopy (SEM) with Energy Dispersive XraySpectroscopy (EDS), X-Ray Diffraction (XRD), Physisorption of Nitrogen at its normal boiling point(77 K) Temperature Programmed reduction (TPR) with hydrogen and electrocatalytic studies indifferent atmospheres using the Electrochemical Impedance Spectroscopy technique (EIS). Theinfluence of the iron content in the physicochemical and electrical properties of the synthesizedsamples is studied.