Synthesis and Evaluation of the A–site Deficient Perovskite La0.65Sr0.3Cr0.85Ni0.15O3-δ as Fuel Electrode for High Temperature Co–electrolysis Enhanced by In Situ Exsolution of Ni Nanoparticles

Abstract

In this work, we focused on the lanthanum strontium chromite (LSC) matrix with the purpose to partially substitute the B-site with an electrocatalytic reducible transition metal that could be exsolved in situ. Therefore, nickel was considered at a substitution level of 15%. In addition, an A-site deficiency was formulated in order to enhance the exsolution capability of the electrocatalyst. A precursor was synthesized by wet-chemical method and further calcined in air. Single phase was obtained with the formulation La0.65Sr0.3Cr0.85Ni0.15O3-δ (L65SCN) which was characterized by X–ray diffraction (XRD) and Rietveld refinement analyses. Exsolution was investigated by means of thermogravimetric analysis (TGA) under reducing conditions and temperature-programmed reduction (TPR). Scanning electron microscopy (SEM) was used to study the particle morphology and its evolution. Ni particle exsolution was observed after exposure to a reducing atmosphere. The behaviour of the L65SCN perovskite was compared with the stoichiometric La0.70Sr0.3Cr0.85Ni0.15O3-δ (L70SCN). Aiming at evaluating the electrochemical performance, electrolyte-supported cells were manufactured by screen printing and sintering of composite L65SCN/CGO as fuel electrode and La0.58Sr0.4Fe0.8Co0.2O3-δ (LSCF) as air electrode on CGO-3YSZ-CGO substrates. The produced cells were tested in electrolysis and co–electrolysis mode and characterized by means of Electrochemical Impedance Spectroscopy (EIS) and polarization curves. Results will be presented with the perspective of SOEC applications.