Suppression of Carbon Deposition on Ni Films by Redox Treatment of Ceria Substrates

For solid oxide fuel cells (SOFCs), ceria is very attractive material used as electrolyte or Ni-cermet. It possesses the fast oxygen transport due to its high concentration of oxygen vacancy under reducing atmosphere. In addition, it was reported that this oxygen vacancy defects can be rapidly formed and eliminated even at room temperature giving it a high oxygen storage capacity. However, it was not expected that the redox ceria can recovery completely after re-oxidized. Since it was reported that ceria can suppress the carbon deposition on Ni surface using Ni-cermet or Ni film supported on ceria, therefore, we want to clear whether or not this redox behavior play an positive role to suppress the carbon deposition on Ni film. In this work, we prepared Ni film with micrometer size on an as sintered Gd doped ceria (GDC) and GDC with redox treatment. We can reproduce the suppression of carbon deposition on Ni film using GDC with redox treatment as the substrate. However, this behavior disappears when as sintered GDC is used as the substrate. It seems that the GDC substrate after a single redox processing helps to suppress the carbon deposition on Ni film. Here, it is considered that large amount of oxygen vacancy and high concentration of electron in GDC after redox treatment play an important role to suppress the carbon deposition on Ni film for Ni/GDC.