NANOPARTICLES FROM WITHIN: EFFECTS OF SYNTHESIS AND STOICHIOMETRY ON EXSOLUTION

Abstract

In this work, we aim to functionalize the surface of a perovskite oxide (ABO₃ structure) with Ni-Fe nanoparticles via the exsolution technique, with the goal of enhancing its electrocatalytic properties as an electrode for solid oxide cells (SOC). Exsolution is a surface-decoration technique based on the controlled segregation of elements originally contained within the host oxide (in our case, Sr(Ti_0.3Fe_0.7)O_3‑δ, referred to as STF). We show how the exsolution of B-site metal cations leads to an excess of Sr at the A-site of the perovskite, which impacts negatively on its electrochemical performance. As a strategy to counteract this effect, we explore the introduction of a Sr deficiency at the A-site of the starting perovskite. Finally, we compare the fabrication of Ni-doped, Sr-deficient STF electrodes (composition Sr_0.93Ti_0.3Fe_0.63Ni_0.07O_3‑δ) using two different synthesis routes: the solid-state reaction method and a sol-gel route.