Anion Fluorine-Doped La0.6Sr0.4Fe0.8Ni0.2O3−δ Perovskite Cathodes with Enhanced Electrocatalytic Activity for Solid Oxide Electrolysis Cell Direct CO2 Electrolysis

As a promising and profound device for energy conversion, a solid oxide electrolysis cell (SOEC) can efficiently convert CO2 to CO, realizing chemical storage of renewable energy. However, developing active and stable cathode catalysts for the CO2 reduction reaction (CO2-RR) is critical for SOECs. Herein, to enhance the electrocatalytic performance of a La0.6Sr0.4Fe0.8Ni0.2O3−δ (LSFN) cathode catalyst for CO2-RR, fluorine doping is investigated as anion doping for O-site in the LSFN perovskite lattice. The results confirm that F-doped La0.6Sr0.4Fe0.8Ni0.2O3−δ (LSFNF0.1) has more oxygen vacancies and better CO2 adsorption ability (approaching 4 times than LSFN). The cell with LSFNF0.1 can achieve a maximum electrolysis current density of 1.93 A·cm–2 at 1.8 V at 850 °C, with a Rp of 0.275 Ω·cm2 at OCV. Meanwhile, the cell possesses good durability for more than 60 h at an electrolysis current density of 0.6 A·cm–2 without apparent degradation. Mechanistic analysis indicates that F-doping can accelerate the formation of intermediates during electrolysis, indirectly promoting the reaction of the bidentate carbonate (rate-determining step). This work shows that anion-doped LSFNF0.1 is a promising cathode for SOEC direct CO2 electrolysis and provides a potential route for the cathode catalyst development of SOECs.