Ma, W.Morales-Vidal, J.Tian, J.Liu, M.T.Jin, S.Ren, W.Taubmann, J.Chatzichristodoulou, C.Luterbacher, J.Chen, H.M.López, N.Hu, X.2025-07-242025-07-242025Nature, 2025; 641(8065):1156-11610028-08361476-4687https://hdl.handle.net/2440/146284Published online: 14 May 2025Electrochemical CO2 reduction into chemicals and fuels holds great promise for renewable energy storage and carbon recycling1,2,3. 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 higher4,5,6,7,8. 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.en© The Author(s) 2025 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.Journal article10.1038/s41586-025-08978-0740271Ren, W. [0000-0002-8769-3131]