Electrochemical Properties of LaCoO₃ Anode for Oxygen Evolution in Molten LiCl–CaCl₂ during CO₂ Decomposition

Development of inert anodes for electrochemical CO2 decomposition is essential for the achievement of carbon-negative emissions. Previous studies have demonstrated that the electrochemical oxygen evolution occurred at a La0.6Sr0.4CoO3−δ anode in chloride-based melts. However, the current efficiency for oxygen evolution was only 54.4%, and dissolution of doped Sr into the melts was observed. For further improvement of anodes, this study investigates LaCoO3 as the anode material. Cyclic voltammetry measurements in LiCl–CaCl2 with CaO and CaCO3 at 873 K showed that current density attributed to the electrochemical oxidation of oxide ions into oxygen increased within a potential range of 2.9–3.3 V vs. Ca(Ⅱ)/Ca. In galvanostatic electrolysis at a current density of 80 mA/cm2 for 15 h, the potential on the LaCoO3 electrode remained within the potential range for oxygen evolution. Gas chromatography analysis of the generated gases during the galvanostatic electrolysis revealed that the current efficiency for oxygen evolution was 91%, while the efficiency for CO2 evolution was 4.8%. The corrosion rate in the galvanostatic electrolysis was γ = 3.8×10-5 g cm−2 h−1, which is sufficiently low to classify the anode as inert. These results demonstrate that LaCoO3 is a promising material for an inert anode in CO2 decomposition.