Robust CO2 electrolysis via in situ interfacial engineering with exsolved Fe nanoparticles on a perovskite cathode

Abstract

Solid oxide electrolysis cells (SOECs) offer a promising route for electrochemical CO₂ conversion to sustainable fuels, but their widespread adoption is hindered by the lack of cathodes combining high catalytic activity and stability. To address this challenge, we developed an in situ interface-engineered La_0.6Sr_0.4Fe_0.95Ti_0.2O_3−δ cathode (R-LSF_0.95T) featuring exsolved Fe nanoparticles. The optimized R-LSF_0.95T-based cell delivers a current density of 780 mA cm⁻² at 1.5 V and 800 °C in a pure CO₂ atmosphere, representing a 23.2% improvement over the mechanically mixed electrode. This performance enhancement arises from synergistic metal-oxide hetero-interfaces, where the reduced perovskite substrate promotes CO₂ adsorption and oxygen-ion transport, while the Fe nanoparticles provide abundant active sites and reduce the activation barrier for CO₂ reduction. Notably, the Fe-decorated perovskite demonstrates superior carbon deposition compared to Ni-based cathodes owing to its moderate activity. Consequently, the electrolysis cell exhibits exceptional stability over 100 h at 1.5 V and 800 °C, with interfacial robustness further enhanced through redox cycling due to a reinforced anchoring effect with more minute nano-Fe exsolution. This work establishes a novel materials design paradigm that reconciles the activity–stability trade-off in SOEC cathodes through the combination of moderately active catalysts with interface reinforcement, offering new pathways for developing durable, high-performance CO₂ electrolysis systems.