Enhancing catalytic activity of CO2 electrolysis via B-site cation doped perovskite cathode in solid oxide electrolysis cell

Abstract

Solid oxide electrolysis cell (SOEC) is considered as a high energy-efficient CO2 conversion method and a promising technology to achieve carbon neutralization. Thus, in this work, the reduced Co or Ni doped Pr0.4Sr0.6Fe0.9Mo0.1O3 perovskite oxides are used as the cathode of SOEC. After reduction, Co-Fe alloy nanoparticles are in situ exsolved from Pr0.4Sr0.6Co0.2Fe0.7Mo0.1O3 and Pr0.4Sr0.6Co0.45Fe0.45Mo0.1O3, and NiFe10.8 alloy nanoparticles are attached on the Pr0.4Sr0.6Ni0.2Fe0.7Mo0.1O3 matrix. The reduced Pr0.4Sr0.6Ni0.2Fe0.7Mo0.1O3 exhibits the highest oxygen vacancy concentration and CO2 adsorption ability, which further promote oxygen surface exchange and electrochemical surface exchange reaction. Besides, the reduced Pr0.4Sr0.6Ni0.2Fe0.7Mo0.1O3 exhibits the highest surface reaction rate constant (kchem) of 3.54 × 10-4 cm s-1 and highest oxygen chemical bulk diffusion coefficient (Dchem) of 27.53 × 10-5 cm2 s-1, suggesting that reduced Pr0.4Sr0.6Ni0.2Fe0.7Mo0.1O3 shows the best catalytic activity for CO2 reduction reaction. The symmetrical cell with reduced Pr0.4Sr0.6Ni0.2Fe0.7Mo0.1O3 shows the lowest polarization resistance (Rp) value, and at 800 °C, the electrolysis cell with reduced Pr0.4Sr0.6Ni0.2Fe0.7Mo0.1O3 cathode also exhibits the best performance of 0.81 A cm-2 in 50%CO-50%CO2 and 1.05 A cm-2 in pure CO2 at 1.5 V, indicating that reduced Pr0.4Sr0.6Ni0.2Fe0.7Mo0.1O3 is a promising cathode for CO2 electrolysis.