Non-perovskite Structural CaFe2O4 with Matched Thermal Expansion Coefficients Exhibiting High Performance for CO2 Electroreduction

Electroreduction of CO2 in solid oxide electrolysis cells is a promising way to convert CO2 to value-added chemicals using renewable electricity. However, the traditional perovskite cathodes suffer from low activity or mismatched thermal expansion coefficients (TECs) compared with other components of cells. Here, a non-perovskite cathode CaFe2O4 that has a matching TEC with other components of the cell was investigated for CO2 electrolysis in solid oxide electrolysis cells. CaFe2O4 undergoes phase transition under electroreduction conditions, producing brownmillerite-structured Ca2Fe2O5 with abundant oxygen vacancies and electro-exsolved Fe nanoparticles, forming active metal/oxide interfaces. The phase transition improves the CO2 adsorption and conductivity and thus promotes the activation of CO2 and electronic transfer. Therefore, this cathode demonstrates high electrochemical performance, reaching a current density of 1.81 A cm(-2) at 1.6 V and 850 degrees C, and exhibits good stability at 1.2 V and 850 degrees C for 325 h. The cathode connects well with other components of cells even after the long-term stability test due to the matching TEC.

Automated summary

The non-perovskite cathode CaFe2O4 has been investigated for CO2 electrolysis in solid oxide electrolysis cells, showing improved CO2 adsorption and conductivity through a phase transition process. The cathode demonstrates high electrochemical performance, reaching a current density of 1.81 A cm(-2) at 1.6 V and 850 degrees C, and exhibits good stability even after long-term testing.