A Strategy to Enhance the Catalytic Activity of Electrode Materials by Doping Bismuth for Symmetrical Solid Oxide Electrolysis Cells

Abstract

Lanthanum chromate-based perovskites are potential ceramic electrodes for symmetrical solid oxide electrolysis cells (Sym-SOECs). In order to improve its electrochemical activity for CO2 reduction reaction (CO2RR), bismuth is introduced into the A-site. While all the components are stable in the anode atmosphere, the cathode application limits the doping content to 0.2, below which bismuth has the suboxidation state between 0 and +3. As revealed with experimental investigations and density functional theory calculations, doping bismuth could effectively increase the physicochemical properties for CO2RR, including oxygen vacancy concentration, CO2 adsorption capacity, conductivities in CO–CO2 atmospheres, oxygen bulk diffusion coefficient, as well as surface exchange coefficient. Consequently, Rp for CO2RR is reduced by 82% to 1.07 Ω cm2 at 800 °C. And the Sym-SOEC performance for CO2 electrolysis is increased by 46% to 0.79 A cm–2 at 800 °C, 1.5 V, indicating that bismuth-doped material is an excellent ceramic electrode material for Sym-SOECs.