Oscillating syngas production on NiO/YSZ catalyst from methane oxidation
Nickel oxide/yttrium-stabilized zirconia (NiO/YSZ) is a state-of-the-art anode used in solid oxide fuel cells (SOFCs). Despite its excellent electrochemical activity in hydrogen fuel cells, there are barriers to the storage of hydrogen, which have stimulated interest in the investigation of chemical reactions on NiO/YSZ involving methane, a major component of natural gas. Many studies have shown that irreversible deactivation of the Ni/YSZ anode (after the reduction of NiO/YSZ) occurs due to the rapid pyrolysis of methane with carbon deposition. The deposited carbon either encapsulates the active site of nickel or removes the nickel metal, thus leading to the destruction of the electrode microstructure and loss of conductivity. Moreover, the formation of carbon is very sensitive to temperature, the concentration of methane, the presence of steam, and the number of oxygen anions present. Consequently, the operation of the Ni/YSZ cermet as a component in an electrochemical cell is demanding. The search for alternative anode materials is widely recognized as an important technical objective in this field.