Medium-Entropy Alloy/Oxide Nano Composite for High-Performing High-Temperature CO2 Electrolysis with Remarkable Carbon Deposition Resistance

Conventional solid oxide electrolysis cells (SOECs) with nickel/yttria-stabilized zirconia (Ni/YSZ) electrodes suffer from low CO₂ 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 CO₂ 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 CO₂ electrolysis in SOECs, significantly contributing to the scalability and practical application of this critical technology.