In Operando Raman Spectroscopy Study on Oxygen Chemical Potential Change in Ni−SDC Cermet Anode for Solid Oxide Fuel Cells

Abstract

The cermet of Ni−oxide ion conductor is widely used as an anode in solid oxide fuel cells (SOFCs). However, the usage of nickel induces various degradation phenomena during discharge operation; e.g., agglomeration and/or oxidation of nickel catalyst, and carbon deposition. In most cases, these degradation phenomena are triggered by the change in the oxygen chemical potential inside the anode. In this study, then, in operando Raman spectroscopy was conducted for the anode of Ni−Ce0.8Sm0.2O2-δ (Ni−SDC) cermet at 700°C with applying SDC as a probe for the detection of oxygen chemical potential. This is because the band related to the oxygen vacancy in the Raman spectrum of SDC varies depending on the partial pressure of oxygen in the ambient atmosphere. The change in oxygen chemical potential at the top surface of anode was successfully quantified under polarization. The effective reaction zone of anode was also discussed by comparing with the data derived from impedance spectra measured simultaneously.