Encapsulated Co–Ni alloy boosts high-temperature CO2 electroreduction

Electrochemical CO₂ reduction into chemicals and fuels holds great promise for renewable energy storage and carbon recycling^1-3. Although high-temperature CO₂ electroreduction in solid oxide electrolysis cells is industrially relevant, current catalysts have modest energy efficiency and a limited lifetime at high current densities, generally below 70% and 200 h, respectively, at 1 A cm^-² and temperatures of 800 °C or higher^4-8. Here we develop an encapsulated Co-Ni alloy catalyst using Sm₂O₃-doped CeO₂ that exhibits an energy efficiency of 90% and a lifetime of more than 2,000 h at 1 A cm^-² for high-temperature CO₂-to-CO conversion at 800 °C. Its selectivity towards CO is about 100%, and its single-pass yield reaches 90%. We show that the efficacy of our catalyst arises from its unique encapsulated structure and optimized alloy composition, which simultaneously enable enhanced CO₂ adsorption, moderate CO adsorption and suppressed metal agglomeration. This work provides an efficient strategy for the design of catalysts for high-temperature reactions that overcomes the typical trade-off between activity and stability and has potential industrial applications.