Achieving High-Efficiency CO2 Electrolysis for SrFeO3-δ-Based Symmetric Electrodes

In situ exsolution of nanoparticles has been reported to be an efficient path to optimize CO2 electrolysis performance. Herein, a Ce/Co co-doped SrFeO3-δ (SF) can achieve the co-exsolution of CeO2 and Co–Fe alloy in 5% H2 at 800 °C. A small amount (<10%) of Ce-doped SF cannot stabilize the perovskite structure in a reducing atmosphere. Sr0.9Ce0.1Fe0.9Co0.1O3 (10Ce10CoF) and Sr0.95Ce0.05Fe0.9Co0.1O3 (5Ce10CoF) as symmetric electrodes of solid oxide electrolysis cells showed an excellent electrolysis performance at 800 °C for CO2 electrolysis. The current densities of the cells with 5Ce10CoF and 10Ce10CoF reached 0.98 and 1.30 A cm–2 under a bias of 1.3 V after a 48 h durability test for CO2 electrolysis, respectively, and the performance difference, however, may be due to CeO2 being more easily exsolved from the 10Ce10CoF lattice. We also investigated the role of the exsolved CeO2 and oxygen vacancy (VO) in determining the CO2 electrolysis performance via theoretical calculation. In this work, we designed a novel strategy to achieve the exsolution of CeO2 and Co–Fe alloy via reduction treatment and showed an outstanding CO2 electrolysis performance.