Confined Cu₁₁₁ Nanolaminates as a Single-Phase Nanoreactor for Efficient Urea Electrosynthesis

Modern electrocatalysis typically involves multi-species cascade systems, imposing stringent requirements on catalysts to exhibit multi-component and multifunctional characteristics. Such complexity poses great challenges for identifying and understanding the structural and functional nature of the true active phase. Herein, we report the formation of Cu₁₁₁ nanolaminates confined within the interface of Cu_1.94S/In₂S₃ heterojunction via in situ electrochemical reconstruction. The synthesized Cu₁₁₁ nanolaminates act as a single-phase co-activating nanoreactor to preferentially adsorb carbon dioxide (CO₂) and cascade N-intermediates, enabling C─N coupling for urea synthesis within an ultra-low and distinct potential window. The optimized Cu_1.94S/Cu₁₁₁/In₂S₃ catalyst achieves a urea yield rate of 11823.65 µg h^-1 mg_Cu111 ^-1 and an exceptionally high Faradaic efficiency of 69.34% at -0.35 V versus the reversible hydrogen electrode in a flow cell, surpassing all previously reported transition metal electrocatalysts. In situ spectroscopic analyses and theoretical calculations reveal a favorable reaction pathway and nanoconfined synergy on the Cu₁₁₁ nanolaminates, where CO₂ is initially anchored and reduced to *CO and cascaded *NO₂ undergoes C─N coupling to form the key *CONO₂ intermediate toward urea. This study unveils the true active phase within a complex heterostructure electrocatalyst, which also provides new insights into the rational design of advanced electrocatalysts for other energy and environmental applications.