Stable high-valent iridium single atoms for high-temperature CO₂ electrolysis

Single-atom catalysts (SACs) offer high atomic efficiency and catalytic activity but are prone to aggregation and degradation under high-temperature conditions. Here, we propose a thermally and electrochemically stable high-valent iridium single atom synthesis strategy based on strong metal-support interactions (SMSI) to enhance high-temperature CO₂ electrolysis performance in solid oxide electrolysis cells (SOECs). The SMSI effect, in situ induced during high-temperature cell fabrication and operation, stabilizes the high-valent iridium single atom and simultaneously modulates the surface electronic structure of the La_0.6Sr_0.4FeO_3-δ (LSF) cathode by weakening the Fe-O hybridization, finally promoting oxygen vacancy formation and enhancing CO₂ adsorption and activation. This approach boosts the CO₂-to-CO electrolysis current density by 80.8% relative to the pristine LSF cathode, achieving 3.02 A cm^-2 at 800°C and 1.5 V with nearly 100% Faradaic efficiency and excellent stability over 600 h. These findings provide a viable strategy for designing thermally and electrochemically robust SACs for high-temperature catalytic reactions.