ABSTRACT 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 Cu 111 nanolaminates confined within the interface of Cu 1.94 S/In 2 S 3 heterojunction via in situ electrochemical reconstruction. The synthesized Cu 111 nanolaminates act as a single‐phase co‐activating nanoreactor to preferentially adsorb carbon dioxide (CO 2 ) and cascade N‐intermediates, enabling C─N coupling for urea synthesis within an ultra‐low and distinct potential window. The optimized Cu 1.94 S/Cu 111 /In 2 S 3 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 Cu 111 nanolaminates, where CO 2 is initially anchored and reduced to *CO and cascaded *NO 2 undergoes C─N coupling to form the key *CONO 2 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.
Zhang et al. (2026) studied this question.