Tunable exsolution of Cu or Fe-Cu bimetallic particles in double perovskite cathode for enhanced CO2 adsorption and catalytic activity in Solid oxide electrolysis cells

Solid oxide electrolysis cells (SOEC) have garnered increasing attention due to their unique capability to integrate CO₂ reduction reaction (CO₂RR) with renewable energy storage. However, a critical challenge facing SOEC devices remains the insufficient electrocatalytic activity and poor durability of fuel electrodes for CO₂RR. In most studies, the developed in situ exsolved perovskite electrodes were directly proposed without discussing the tunability of exsolved particles during the reduction process. Herein, the effects of the control of reduction time and the selection of specifically exsolved elements on the electrochemical performance of the electrodes are investigated. The in-situ construction of hetero-structured DP-SFMC composites with exsolved Cu metal particles (R-SFMC-2 h) and Fe-Cu bimetallic particles (R-SFMC-5 h) was successfully achieved through a one-step reduction treatment of Sr_1.9Fe_1.5Mo_0.3Cu_0.2O_6-δ (SFMC) perovskite at 800 ℃ for 2 h and 5 h, respectively. The R-SFMC-2 h and R-SFMC-5 h exhibited superior CO₂ electrolysis performance. At 800 ℃ under an applied potential of 1.5 V, the CO₂ electrolysis current densities reached approximately 1.73 and 1.53 A cm⁻², respectively, significantly outperforming single cells with pristine SFMC cathode (0.99 A cm⁻²) and other promising electrodes.