Stabilizing Cu⁰/Cu⁺ Interfaces via High-Entropy Electrochemical Potential Regulation Strategy for Enhanced CO₂-to-Ethylene Conversion in Acidic Medium

The electrochemical CO₂ reduction reaction (CO₂RR) in acidic media represents an efficient carbon-negative strategy, mitigating greenhouse effects while selectively producing value-added multi-carbon compounds. The Cu⁰/Cu⁺ interfaces could promote C─C coupling processes, but preserving the interface integrity under highly reductive potentials and acidic conditions presents substantial challenges. Here, a high-entropy electrochemical potential regulation strategy is reported that leverages high-entropy doping synergy to atomically tailor the surface electronic structure of Cu-based catalysts. This strategy creates an electron shield effect around the host element (Cu), protecting it from excessive reduction and facilitating the formation and stabilization of Cu⁰/Cu⁺ interfaces during acidic CO₂RR. Comprehensive operando characterizations combined with density functional theory calculations reveal that the electron shield effect strategically modulates the electron-accepting capability of Cu. The optimized surface electronic structure facilitates C─C coupling, significantly enhancing the CO₂-to-C₂₊ conversion efficiency. The designed catalyst achieves a remarkable Faradaic efficiency of 66.7% for ethylene production at −1.69 V vs the reversible hydrogen electrode in acidic electrolyte (pH 2), while maintaining excellent stability with an average ethylene Faradaic efficiency of 63.1% over 52-h continuous operation. This work establishes a new strategy for designing and stabilizing active interfaces of copper-based electrocatalysts for efficient and durable acidic CO₂ electroreduction.