YANG Xianghao ¹, ZHAO Xianxing ^2, LI Jingyun ², TIAN Yunfeng ³, CHI Bo ¹

(1. School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, Hubei, China; 2. ENNGroup, Langfang 065001, Hebei, China; 3. School of Materials Science and Physics, China University of Mining and Technology, Xuzhou 221116, Jiangsu, China)

Abstract: Electrocatalysis of CO₂ splitting is an important strategy for carbon neutrality. Symmetrical solid oxide cell (SSOC), adapting the same oxide materials as both the cathode and anode, has been extensively recognized for CO₂ electrolysis, due to its high energy conversion efficiency, simple cell interfaces and low cost. One of the key challenges to its industrialization is the lack of efficient electrocatalyst for both oxygen evolution and CO₂ electrolysis. In this work, La_1-xBa_xFe_0.8Ni_0.2O_3-δ (LBxFN, x=0.2, 0.4, 0.5, 0.6, 0.8) perovskite oxides were synthesized via a conventional sol-gel method, which were evaluated as potential symmetrical electrodes of SSOC for electrochemical reduction of pure CO₂. The effects of substituting Ba for La on crystalline structure and electrochemical performance of the samples were comprehensively studied. The LB_0.4FN electrode showed the lowest polarization resistance of 0.02 Ω•cm² in air and 0.18 Ω•cm² in CO₂ at 800 ℃. A current density of 1.12 A•cm^-2 at 1.8 V was obtained with pure CO₂ feed gas in an electrolyte -supported SSOC at 800 ℃ with the LB_0.4FN electrode. The replacement of La by Ba could not only improve the oxygen evolution reaction catalytic activity, but also enhance the CO₂ electrolysis performance. Therefore, Ba-doped LB_0.4FN material is a promising symmetrical electrode material for SSOC.

Key words: solid oxide electrolysis cell; symmetrical solid oxide cells; CO₂ electrolysis; electrochemical performance