Self-optimized and stable nanocomposites via one-pot synthesis for high-temperature CO₂ electrolysis in solid oxide electrolysis cells

Solid oxide electrolysis cells (SOECs) hold the promise of directly converting CO₂ into CO fuels with exceptional cost-effectiveness and efficiency. However, the widespread application of SOECs is impeded by the significant lack of highly active and stable cathodes. Herein, a one-pot synthesis strategy is proposed to introduce Cu into a composite consisted of Sr₂Fe_1.5Mo_0.5O_6−δ (SFM) and Gd_0.2Ce_0.8O_1.9 (GDC). This strategy leads to the automatic formation of hetero-structured composites, comprising double perovskite, Ruddlesden-Popper perovskite, fluorite, as well as in-situ exsolved Cu–Fe bimetals at high temperatures and operational conditions. Consequently, this approach greatly enhances CO₂ adsorption capability, CO₂ catalytic activity, O²⁻/e⁻ conductivity, and ensures good phase compatibility with electrolyte. As results, the La_0.8Sr_0.2Ga_0.8Mg_0.2O_3−δ electrolyte-supported single cell with the composite cathode achieves a high current density of 2.22 A cm⁻² at 850 °C and 1.6 V, which is substantial increase of 65.7% compared to the current density achieved with traditional physically hybrid SFM-GDC cathodes. These results underscore the potential of one-pot synthesized nanocomposites as promising cathodes for CO₂ electrolysis in SOECs.