Ternary Fe- or Mo-Au-Ni/GDC as Candidate Fuel Electrodes for the Internal Dry Reforming of CH₄: Physicochemical and Kinetic Investigation

The present study deals with the physicochemical and catalytic/kinetic investigation of Fe, Au, Fe-Au, and Mo-Au modified Ni/GDC electrocatalysts towards their performance for the DRM, RWGS, and CH4 decomposition reactions. For this purpose, Au-NiO/GDC (where Au = 1 or 3 wt.%), Fe-NiO/GDC (where Fe = 0.5 or 2 wt.%), 0.5Fe-3Au-NiO/GDC, and 0.4Mo-3Au-NiO/GDC were synthesized via deposition (co-) precipitation. There is discussion on the structural properties of the electrocatalysts on the oxidized and reduced state, as well as their use as electrolyte-supported (half) cells. A key remark after H-2-reduction is the formation of binary or ternary solid solutions. Ni/GDC was the most active for the catalytic CO2 reforming of CH4 and the CH4 decomposition reactions and as a result the most prone to carbon deposition. On the other hand, the modified 3Au-Ni/GDC, 0.5Fe-3Au-Ni/GDC, and 0.4Mo-3Au-Ni/GDC exhibited the following properties: (i) the highest E-a,E-app for the non-desired RWGS reaction, (ii) high tolerance to carbon formation due to lower activity for the CH4 decomposition, and (iii) were also less active for H-2 and CO production. Finally, 0.4Mo-3Au-Ni/GDC seems to perform the DRM reaction through a different mechanism when compared to Ni/GDC. Overall, the above three samples are proposed as potential fuel electrodes for further electrocatalytic measurements for the SOFC internal DRM process.