Methane On-Cell Reforming by Alloys Reduced from Ni0.5Cu0.5Fe2O4for Direct-Hydrocarbon Solid Oxide Fuel Cells

Ni 0.5 Cu 0.5 Fe 2 O 4 (NCFO)-Gd 0.1 Ce 0.9 O 1.95-δ (GDC) composite was imposed on NiO-Y 2 O 3 stabilized ZrO 2 (YSZ) anode by screen-printing and sintering, and reduced in situ to form a layer of metal (Ni-Fe and Ni-Cu alloys, NCF)-GDC cermet on Ni-YSZ, functioning as a catalyst for CH 4 on-cell reforming. The double-layer anode NCF-GDC/Ni-YSZ (DA) was investigated by electrochemical impedance spectroscopy and direct current polarization in H 2 -3 mol% H 2 O and CH 4 -x mol% H 2 O (x = 3 ∼ 20) at various temperatures between 650 and 800°C. For comparison single-layer Ni-YSZ anode (SA) was also evaluated. The polarization resistance of the DA decreased to 1/3 and 1/2 of that of the SA in H 2 -3 mol% H 2 O and CH 4 -3 mol% H 2 O, respectively, due to the increase in anode thickness and carbon deposition resistance. This improvement was also supported by the results of direct current polarization, SEM examination and Ramann spectroscopy. Carbon deposition was avoided in the DA during the test at 800°C and 200 mA cm −2 for 24 h by slightly increasing the H 2 O content to the level of 7 mol% in the CH 4 -H 2 O mixture. Excessive amount of H 2 O (20 mol% H 2 O) was found to deteriorate the electrochemical performance of the DA by fuel dilution.