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

Lanthanum chromate-based perovskites are potential ceramic electrodes for symmetrical solid oxide electrolysis cells (Sym-SOECs). In order to improve its electrochemical activity for CO 2 reduction reaction (CO 2 RR), 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 CO 2 RR, including oxygen vacancy concentration, CO 2 adsorption capacity, conductivities in CO–CO 2 atmospheres, oxygen bulk diffusion coefficient, as well as surface exchange coefficient. Consequently, R p for CO 2 RR is reduced by 82% to 1.07 Ω cm 2 at 800 °C. And the Sym-SOEC performance for CO 2 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.