Enhancement of anode activity and stability by Cr addition at Ni/Sm-doped CeO2 cermet anodes in NH3-fueled solid oxide fuel cells

Chromium was added to nickel/Sm2O3-doped ceria (Ni/SDC) cermets by a CrCl3 impregnation method, and the activity of the resulting Ni-Cr/SDC cermets was evaluated as anodes in ammonia-fueled solid oxide fuel cells (SOFCs) in the temperature range of 773 to 1173 K. It has been revealed that the addition of Cr was effective for the catalytic activity for NH3 reforming, followed by hydrogen oxidation. The optimum amount of Cr was 3 at.% of the total metal in the Ni-Cr/SDC cermets. In addition, we demonstrated the improved stability of the Ni97-Cr3/SDC cermets in NH3 atmosphere at 873 K. The addition of Cr suppressed the agglomeration of Ni, and promoted the anode durability. XRD analysis suggested the formation of a nitride CrN during operation in the Ni97-Cr3/SDC anode, and the role of the nitride was discussed in detail.