Stable power generation using a solid oxide fuel cell with a Ni/Gd-doped CeO2 Cermet anode in 100% dry-CH4 fuel based on the anode reaction mechanism

Stable power generation from a solid oxide fuel cell (SOFC) with a Ni/ Gd-doped CeO2 Cermet (GDC) anode in 100% dry-methane (CH4) fuel was achieved at a maximum power density of 170 mW/ cm(2) at 900 degreesC. The SOFC did not degrade even after 120 h of operation. The DC polarization of the Ni/ GDC anode in hydrogen (H-2) fuel and in 4.5% dry-methane fuel was measured by the current interruption method and then compared with those of Ni/YSZ, Pt/YSZ and Pt anodes. The apparent reaction orders of the oxygen activity for Ni/GDC anodes in both hydrogen fuel and 4.5% dry-methane fuel were smaller than those for Ni/YSZ, Pt/YSZ, and Pt anodes. Based on the previously proposed anode reaction mechanism for Ni/YSZ and Pt/YSZ anodes in hydrogen fuel and 4.5% dry-methane fuel, the stable power generation of the SOFC with the Ni/GDC anode in 100% dry-methane fuel was probably due to the high equilibrium constant between the oxygen in YSZ and the oxygen on the three-phase boundary on the anodes.