Medium‐Entropy Alloy/Oxide Nano Composite for High‐Performing High‐Temperature CO 2 Electrolysis with Remarkable Carbon Deposition Resistance

Abstract Conventional solid oxide electrolysis cells (SOECs) with nickel/yttria‐stabilized zirconia (Ni/YSZ) electrodes suffer from low CO 2 reduction activity and severe carbon deposition below 800 °C, limiting scalability. This study introduces a novel medium‐entropy alloy/Mn‐based oxide composite catalyst deposited via simple infiltration onto the fuel electrode, creating hierarchical heterogeneous metal/oxide nano‐interfaces. The catalyst‐decorated cell achieves a remarkable 46% increase in CO 2 electrolysis current density, reaching 2.15 A cm −2 at 1.5 V and 750 °C. Simultaneously, the catalyst demonstrates exceptional carbon deposition resistance, evidenced by a 75% increase in the current density threshold for carbon formation. The cell maintains stable, carbon‐free operation for 200 h at an extreme current density of 1.0 A cm −2 . Comprehensive analyses combining in situ characterization and density functional theory (DFT) calculations revealed the enhanced performance originates from synergistic effects between the unique composition of the medium‐entropy alloy and Mn‐based oxides, and their distinctive nanostructured interfaces. This work presents a promising approach for developing advanced electrode materials for CO 2 electrolysis in SOECs, significantly contributing to the scalability and practical application of this critical technology.