Copper-Enhanced CO₂ Electroreduction in SOECs

Abstract

The development of a Co-free and Ni-free electrocatalyst for carbon dioxide electrolysis would be a turning point for the large-scale commercialization of solid-oxide electrolysis cells (CO2–SOECs). Indeed, the demand for cobalt and nickel is expected to become critical by 2050 due to automotive electrification. Currently, the reference materials for CO2–SOEC electrodes are perovskite oxides containing Mn or Co (anodes) and Ni-YSZ cermets (cathodes). However, issues need to be addressed, such as structural degradation and/or carbon deposition at the cathode side, especially at high overpotentials. This work designs the 20 mol % replacement of iron by copper in La0.6Sr0.4FeO3−δ as a multipurpose electrode for CO2–SOECs. La0.6Sr0.4Fe0.8Cu0.2O3−δ (LSFCu) is synthesized by the solution combustion method, and iron partial substitution with copper is evaluated by X-ray powder diffraction with Rietveld refinement, X-ray photoelectron spectroscopy, thermogravimetric analyses, and electrical conductivity assessment. LSFCu is tested as the SOEC anode by measuring the area-specific resistance versus T and pO2. LSFCu structural, electrical, and electrocatalytic properties are also assessed in pure CO2 for the cathodic application. Finally, the proof of concept of a symmetric LSFCu-based CO2–SOEC is tested at 850 °C, revealing a current density value at 1.5 V of 1.22 A/cm2, which is remarkable when compared to similar Ni- or Co-containing systems.