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

An appropriate Cu0/Cu+ interface and interfacial water environment have been proven to be crucial in efficient CO2 electroreduction (CO2RR). However, simultaneously and precisely controlling both factors through a single strategy remains challenging, which limits the high-efficiency CO2RR. 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 CO2RR to ethylene (C2H4), demonstrating universal applicability across diverse Cu-based electrodes. Notably, high C2H4 selectivity is achieved over Cu0.7–CuO0.3, 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 Cu0/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 C2H4 production.