The promoting effect of Fe on Ni/GDC for the Solid Oxide H2O electrolysis

The study deals with the modification of commercial Ni/GDC powder with iron and its use as fuel functional electrode for Solid Oxide H2O electrolysis. The Fe-NiO/GDC samples were prepared with the Deposition-Precipitation method and characterized, in their oxidized and reduced form, by using BET, HR-TEM, SAED, XRD, XPS and TG analysis in the presence of H2O. The electrochemical investigation deals with the comparison of single SOECs at 900 degrees C, under variouspH(2)O/pH(2)ratios. In the oxidized powders iron was detected, both in the bulk and on the surface, in the form of crystallized Fe(2)O(3)species, which during H-2-reduction interacted with NiO towards the formation of a Ni-Fe alloy. The latter promoted the electrochemical performance of the Fe-Ni/GDC electrodes, where there are indications of strong dependence on the Fe wt% content. Specifically, the performance of the cell with 0.5 wt% Fe-Ni/GDC was threefold higher than that with Ni/GDC. On the other hand, the cell with 2 wt% Fe-Ni/GDC was worse, implying that the promoting effect of Fe lies on quite low wt% content. Finally, the examined Fe-doped electrodes exhibited increase of polarization in highpH(2)O. This is primarily ascribed to the fact that Fe-Ni/GDC electrodes seem more susceptible to H2O oxidation. Overall, Fe is considered as a promising Ni/GDC dopant, capable to substitute noble metals like Au, but further investigation is required for the elucidation of key preparation and performance parameters.