BaZr_0.1Ce_0.7Y_0.1Yb_0.1O _3-δ enhanced coking-free on-cell reforming for direct-methane solid oxide fuel cells

A novel anode with a Ni_0.5Cu_0.5Fe₂O ₄ (NCFO)-BaZr_0.1Ce_0.7Y_0.1Yb _0.1O_3-δ (BZCYYb) composite on NiO-Y ₂O₃ stabilized ZrO₂ (YSZ) is fabricated and investigated in dry and wet (3 mol% H₂O) CH₄ at temperatures ranging from 650 to 800 °C. For comparison, a conventional NiO-YSZ anode is also prepared. In H₂-3 mol% H₂O at 600 °C for 2 h, NCFO and NiO are fully reduced to Ni-Cu-Fe alloys (NCF) and Ni, respectively, forming bi-layer NCF-BZCYYb/Ni-YSZ (BL) and single-layer Ni-YSZ (SL) anodes. The polarization resistance of the BL anode in dry and wet CH ₄ is only approximately 1/5 of that of the SL anode due to the enhancement of NCF-BZCYYb on CH₄ oxidation. This improvement is also supported by the results from DC polarization. Carbon deposition is inhibited in the BL anode by adding only 3 mol% H₂O into dry CH₄ and the carbon formed in dry CH₄ can be removed by subsequent exposure of the BL anode to wet CH₄. The overall electrochemical performance of the BL anode is significantly stable in wet CH₄, which suggests that it is promising for applications in direct CH₄ solid oxide fuel cells (SOFCs). This journal is