Perovskite Oxyfluoride Ceramic with In Situ Exsolved Ni-Fe Nanoparticles for Direct CO 2 Electrolysis in Solid Oxide Electrolysis Cells.

Solid oxide electrolysis cell (SOEC) is a potential technique to efficiently convert CO 2 greenhouse gas into valuable fuels. Thus, there is significant interest in developing highly active and stable electrocatalysts for the CO 2 reduction reaction (CO 2 RR). Herein, a Ni and F co-doping strategy is proposed to facilitate the exsolution reaction and form a new cathode, Ni-Fe alloy nanoparticles embedded in ceramic Sr 2 Fe 1.5 Mo 0.5 O 6-δ (SFM) doped with fluorine. F-doping and Ni-Fe exsolution enhance CO 2 adsorption by a factor of 2.4 and increase the surface reaction rate constant ( k chem ) for CO 2 RR from 6.79 × 10 -5 to 18.1 × 10 -5 cm s -1 , as well as the oxygen chemical bulk diffusion coefficient ( D chem ) from 9.42 × 10 -6 to 19.1 × 10 -6 cm 2 s -1 at 800 °C. Meanwhile, the interfacial polarization resistance ( R p ) decreases by 52%, from 0.64 to 0.31 Ω cm 2 . At 800 °C and 1.5 V, an extremely high current density of 2.66 A cm -2 and a stability test over 140 h are achieved for direct CO 2 electrolysis in the SOEC.