Mechanism and kinetics of oxygen reduction on porous Nd2NiO4+δ electrodes with different microstructures.

L. MOGNI.; A. MONTENEGRO HERNÁNDEZ; YAKAL-KREMSKI, K.; A.CANEIRO; S. BARNETT

Mount Holyoke, MA.

Conferencia; Gordon Research Conference: Solid State Studies in Ceramics; 2014

The oxygen reduction kinetics on porous Nd2NiO4+δ  electrodes was studied by combining electrochemical characterization using Impedance Spectroscopy (EIS) with microstructural characterization by 3D tomography performed by focused ion beam-scanning electron microscopy (FIB-SEM). The Nd2NiO4+δ (NNO) is a mixed ionic electronic conductor in which the O-ion migration is by O-interstitials defects located in the NdO layer. Then the oxygen electrode reaction is controlled by the kinetics of incorporation and diffusion of this kind of defects.   The influence of the electrode microstructure was evaluated by comparing NNO electrodes, synthesized with three different methods giving place to diverse microstructures. The EIS spectra were fitted by using electrical equivalent circuit (EEC) where the high frequency response was modeled with a Gerischer-like impedance and the low frequency  with a R//C circuit. The oxygen diffusion coefficients (DO) and the oxygen exchange coefficients (kO) were evaluated applying the Adler-Lane-Steele (ALS) approach between 500 and 700 °C as a function of the oxygen partial pressure (pO2).