In Situ Electrochemical X-ray Spectromicroscopy Investigation of the Reduction/Reoxidation Dynamics of Ni-Cu Solid Oxide Fuel Cell Anodic Material in Contact with a Cr Interconnect in 2 x 10-6 mbar O2

Following our systematic investigations on the durability of solid oxide fuel cell (SOFC) components (Bozzini, B.; Tondo, E.; Prasciolu, M.; Amati, M.; Kazemian, M.; Gregoratti, L.; Kiskinova, M. ChemSusChem, http://dx.doi.org/10.1002/cssc.201100140), the present in situ scanning photoelectron microscopy study is focused on the redox behavior of Ni-Cu bilayers in contact with Cr, representing the anodic material and interconnects for SOFCs, respectively. The experiments with this model cell, using yttria-stabilized zirconia (YSZ) electrolyte, were carried out in 2 x 10(-6) mbar O-2 at 650 degrees C at open circuit potential (OCP) and under applied potential. The elemental images and the spectra from selected parts of the cell have revealed dramatic compositional and inorphological changes under OCP conditions, yielding Ni-Cu islands covered with NiO in the electrode region and a NiO network in the YSZ electrolyte region. The Ni reduction dynamics as a function of applied potential is followed by continuous monitoring of the evolution of the Ni 2p spectra in different regions, which allowed the location of electrochemically active areas of the half-cell upon cathodic polarization. It was shown that after electrochemical reduction the reoxidation at OCP results in notable morphology alterations of the triple-phase contact region, which can be related to the empirically observed degradation of catalytic performance.