Exsolution of nanoparticles from doped LaAlO₃ perovskite at low temperature for reversible solid oxide cell electrode applications

The need to meet rising worldwide energy demand has accelerated the creation and implementation of new technologies and renewable energy sources to progressively replace fossil fuels as the dominant energy providers. Unfortunately, the full replacement of these conventional sources is still far from becoming a reality due to multidimensional factors that are economic, environmental, geopolitical, strategic, and technical in nature. Although not all of the problems can be solved at once, much remains to be done with regards to the technical aspect. There is always a need to develop creative ways to surpass specific challenges, and in the case of current renewable sources, one outstanding obstacle is energy storage. The production of green hydrogen through use of reversible solid oxide cells could offer an alternative solution to conventional battery systems. However, like any other technology, solid oxide cells have their own limitations. This is especially true with the fuel-side electrode, where NiO continues to dominate as the material of choice. Continuous development of a new generation of electrodes with reduced content of critical raw materials and improved electrochemical performance is essential to find an alternative to NiO based electrodes. One promising approach is the combination of exsolution and defects introduced via doping in perovskite oxides. In this work, the operating conditions of the reversible solid oxide cells was taken advantage of to exsolve metallic nanoparticles on the perovskite electrode material surface. It has been proven that well-anchored and dispersed exsolved metallic nanoparticles exhibit both higher electrocatalytic activity as well as better stability via agglomeration resistance when compared to NiO. However, one drawback with exsolution is that it typically requires high temperatures and highly reducing environments to be triggered. In this work, the material properties of LaAlO₃ were enhanced to achieve exsolution at 500°C as well as improving electrochemical performance. This research explores the implementation of doped-LaAlO₃ perovskite oxide, a material with excellent capabilities for exsolution, for Reversible Solid Oxide Cell (r-SOC) electrode applications at temperatures below 600°C. This work follows a pathway that starts with synthesis optimisation and continues to the final application of the material as a fuel-side electrode in a device operating below 600°C. Various complications were encountered along the way and solved in turn, ultimately leading to remarkable results in exsolution.