In-situ Raman spectroscopy analysis of the interfaces between Ni-based SOFC anodes and stabilized zirconia electrolyte

A novel experimental approach for in-situ Raman spectroscopy of the electrode | solid electrolyte interfaces in controlled atmospheres, based on use of the optically transparent single-crystal membranes of stabilized cubic zirconia, was proposed and validated. This technique makes it possible to directly access the electrochemical reaction zone in SOFCs by passing laser beam through the single-crystal electrolyte onto the interface, in combination with simultaneous electrochemical measurements. The case study centered on the analysis of NiO reduction in standard cermet anodes under open-circuit conditions, demonstrated an excellent agreement between the observed kinetic parameters and literature data on nickel oxide. The porous cermet reduction kinetics at 400-600 °C in flowing H2-N2 gas mixture can be described by the classical Avrami model, suggesting that the reaction rate is determined by metal nuclei growth limited by Ni diffusion. The advantages and limitations of the technique are briefly addressed.