Fluorine-doped perovskite cathodes with boosted electrocatalytic activity for CO2 electrolysis

Abstract

Global energy demands that have traditionally been satisfied by the use of fossil fuels have led to substantial emissions of CO₂, an important greenhouse gas. Solid oxide electrolysis cells (SOECs) offer a practical approach for transforming CO₂ into valuable fuels. Accordingly, creating stable electrocatalysts and perovskite cathodes capable of efficiently converting CO₂ is a primary aim for the further development of SOECs. Although reconstructing active sites during CO₂ electrolysis is significantly challenging, it is also constrained by our lack of understanding of this process. Herein, we introduce an innovative strategy that involves co-doping with Cu and F to better facilitate the exsolution reaction, which resulted in the formation of an advanced cathode composed of Cu-Fe alloy nanoparticles embedded in a fluorine-doped Sr₂Fe_1.5Mo_0.5O_6−δ (SFM) ceramic matrix. The in-situ electrochemical reconstruction of the SFM cathode through co-doping not only improves mass-transfer efficiency during CO₂ electrolysis but also enhances the catalytic activity and durability of the ceramic cathode. A SOEC assembled with this material as a symmetrical electrode delivered 4.99 mL min⁻¹ cm⁻² of CO at 850 °C and an applied voltage of 1.8 V, which is 168 % higher than that of a pure SFM electrode. In addition, no carbon deposits were observed at the end of the reaction. The co-doping strategy delivered enhanced performance without degradation over 100 h of high-temperature operation, which suggests that it is a reliable cathode material for CO₂ electrolysis. This study introduced an innovative method for improving the SOEC-electrode microstructure and developing efficient electrocatalysts for CO₂ electrolysis.