BaZr0.1Ce0.7Y0.1Yb0.1O3−δenhanced coking-free on-cell reforming for direct-methane solid oxide fuel cells

Abstract

A novel anode with a Ni0.5Cu0.5Fe2O4 (NCFO)–BaZr0.1Ce0.7Y0.1Yb0.1O3−δ (BZCYYb) composite on NiO–Y2O3 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 CH4 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).