Effect of preparation method on the properties of nanostructured gadolinia-doped ceria materials for IT-SOFCs

In order to obtain different morphologies, nanostructured Gd0.1Ce0.9O1.95 (GDC10) and Gd0.2Ce0.8O1.90 (GDC20) were synthesized using three different chemical methods: reverse microemulsion (RM), cation complexation (CC) and template-filling (TF). The resulting materials were characterized by synchrotron radiation X-ray diffraction (SR-XRD), by X-ray absorption near-edge spectroscopy (XANES) and by scanning and high resolution transmission electron microscopy (SEM and HRTEM). All nanostructured mixed oxides were found to have a cubic crystal phase (Fm3m space group) with an average crystallite sizes ranging from 9.6 to 13.2 nm. Tubular nanostructured GDC10 obtained using a template-filling method exhibited the largest specific surface area (97 m2 g−1) while the lowest values were obtained using the cation complexation method (23 m2 g−1). XANES results indicated that the extent of reduction of these materials was small. Nevertheless, the Ce3+ ion was detected. Preliminary catalytic studies showed that the tubular nanostructured (TF) GDC10 samples exhibited better catalytic activity for CH4 oxidation than the CC and RM nanopowders of the same chemical composition.