Electrocatalytic performance and carbon tolerance of ternary Au-Mo-Ni/GDC SOFC anodes under CH4-rich Internal Steam Reforming conditions

The present work examines the effect of Au-Mo modification on the electrocatalytic performance and carbon tolerance of Ni/GDC for the internal CH4 steam reforming reaction. Comparative electrocatalytic measurements are presented between cells that comprise Ni/GDC and 3Au-3Mo-Ni/GDC as anodes under CH4-rich feed (S/C = 0.3), without dilution in a carrier gas. Complementary electrochemical and physicochemical characterization was performed to investigate the possible modifications on the electrochemical and structural properties of the electrodes. In brief, the cell with Ni/GDC was more active catalytically, but exhibited worst electrocatalytic performance and operated for significantly shorter period with a degradation rate 5.5 mV/h. The main degradation factor was the higher carbon formation rate, which increased gradually and affected the polarization resistance of the electrode. The cell with 3Au-3Mo-Ni/GDC was moderately active catalytically, but performed better and lasted for the double operating period with a degradation rate 2.6 mV/h. In the latter case the carbon formation rate was almost negligible and degradation was attributed to the gradual re-oxidation of nickel, which affected the ohmic resistance of the electrode.