Fe-Doped Ceria-Based Ceramic Cathode for High-Efficiency CO₂ Electrolysis in Solid Oxide Electrolysis Cell

In the quest for sustainable energy solutions, solid oxide electrolysis cell (SOEC) emerges as a key technology for converting CO₂ into fuels and valuable chemicals. This work focuses on pure ceramic Fe_xSm_0.2Ce_0.8O_{2- δ} (xFe-SDC) as the fuel electrodes, and Sr-free ceria-based ceramic electrodes can be successfully constructed for x ≤ 0.05. The incorporation of Fe into the ceria lattice increases the oxygen vacancy concentration and promotes the formation of catalytic sites crucial for the CO₂ reduction reaction (CO₂RR). Density functional theory calculations indicate that Fe enhances electrochemical performance by decreasing the CO₂RR energy barrier and facilitating oxygen ion diffusion. At 800 °C and 1.5 V, single cells with 0.05Fe-SDC cathodes manifest attractive performance, attaining current densities of -1.98 and -2.26 A cm^-2 under 50% CO₂/CO and pure CO₂ atmospheres, respectively. These results suggest the great potential of xFe-SDC electrodes as promising avenues for high-performance fuel electrodes in SOEC.