Unveiling the exsolution mechanisms and investigation of the catalytic processes of Sr2FeMo0.65Ni0.35O6-δ using in situ transmission electron microscopy

Abstract

Solid oxide cells (SOCs) are likely to play crucial role in the green energy transition, but their widespread adoption is hindered by degradation issues, particularly catalyst agglomeration. Nanoparticle exsolution in double-perovskite materials offers a promising solution by creating electrode materials with stable metallic nanocatalysts strongly bonded to the parent oxide, mitigating high-temperature agglomeration issues. Thus, understanding the dynamic evolution of microstructure and catalytic behavior in such materials is vital for developing high-performing SOC catalysts. This study utilized a multimodal approach to investigate the dynamics of exsolution in Sr₂FeMo_0.65Ni_0.35O_6-δ (SFM-Ni) and its effect on cell performance. In situ environmental transmission electron microscopy (ETEM), in situ transmission electron microscopy (TEM) coupled with mass spectrometry visualized the formation and the stability of exsolved particles especially at the concave faces of the parent material during chemical conversion of CO from CO₂. Simultaneously, macro-scale cell experiments coupled with electrochemical impedance spectroscopy, and focused ion beam-scanning electron microscopy (FIB-SEM) tomography, apart from verifying the nanoscale observations, provided crucial insights into the correlation between the exsolution process observed at the micro-scale and the overall cell performance. These findings offers valuable insights into the design and optimization of improved electrode materials for SOCs. Understanding the dynamic behavior of exsolved catalysts would help in enhancing the electrochemical performance at both the nano and macro levels, ultimately advancing the field of sustainable energy technologies.