Atomistic Insights into Medium-Entropy Perovskites for Efficient and Robust CO2 Electrolysis

Solid oxide electrolysis cells (SOECs) show great promise in converting CO₂ to valuable products. However, their practicality for the CO₂ reduction reaction (CO₂RR) is restricted by sluggish kinetics and limited durability. Herein, we propose a novel medium-entropy perovskite, Sr₂(Fe_1.0Ti_0.25Cr_0.25Mn_0.25Mo_0.25)O_6-δ (SFTCMM), as a potential electrode material for symmetrical SOEC toward CO₂RR. Experimental and theoretical results unveil that the configuration entropy of SFTCMM perovskites contributes to the strengthened metal 3d-O 2p hybridization and the reduced O 2p bond center. This variation of electronic structure benefits oxygen vacancy creation and diffusion as well as CO₂ adsorption and activation and ultimately accelerates CO₂RR and oxygen electrocatalysis kinetics. Notably, the SFTCMM-based symmetrical SOEC delivers an excellent current density of 1.50 A cm^-2 at 800 °C and 1.5 V, surpassing the prototype Sr₂Fe_1.5Mo_0.5O_6-δ (SFM, 1.04 A cm^-2) and most of the state-of-the-art electrodes for symmetrical SOECs. Moreover, the SFTCMM-based symmetrical SOEC demonstrates stable CO₂RR operation for 160 h.