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

Solid oxide electrolysis cells (SOECs) show great promise in converting CO to valuable products. However, their practicality for the CO reduction reaction (CORR) is restricted by sluggish kinetics and limited durability. Herein, we propose a novel medium-entropy perovskite, Sr(FeTiCrMnMo)O (SFTCMM), as a potential electrode material for symmetrical SOEC toward CORR. 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 CO adsorption and activation and ultimately accelerates CORR and oxygen electrocatalysis kinetics. Notably, the SFTCMM-based symmetrical SOEC delivers an excellent current density of 1.50 A cm at 800 °C and 1.5 V, surpassing the prototype SrFeMoO (SFM, 1.04 A cm) and most of the state-of-the-art electrodes for symmetrical SOECs. Moreover, the SFTCMM-based symmetrical SOEC demonstrates stable CORR operation for 160 h.