Electrolyte-Mediated Cu 0 /Cu + Interface Stabilization and Interfacial Water Regulation for Enhanced CO 2 Electroreduction to Ethylene

An appropriate Cu 0 /Cu + interface and interfacial water environment have been proven to be crucial in efficient CO 2 electroreduction (CO 2 RR). However, simultaneously and precisely controlling both factors through a single strategy remains challenging, which limits the high-efficiency CO 2 RR. Drawing inspiration from the biuret assay in protein analysis, we introduce biuret (BU) as a multifunctional electrolyte additive that concurrently stabilizes Cu + active sites and restructures the interfacial water network under electrochemical conditions. The combined effect of the above two factors enables efficient CO 2 RR to ethylene (C 2 H 4 ), demonstrating universal applicability across diverse Cu-based electrodes. Notably, high C 2 H 4 selectivity is achieved over Cu 0.7 –CuO 0.3, with a Faradaic efficiency of 65.1% at a partial current density of 802.6 mA cm –2 . In situ spectroscopy and theoretical calculations demonstrate that BU induces the formation of a distinctive Cu 0 /Cu + interface and reconstructs the interfacial hydrogen-bonding network. This cooperative modulation significantly reduces the free energy barrier for asymmetric *CO–*CHO coupling, favoring selective C 2 H 4 production.