The study investigates the rate-determining steps (RDS) on copper (Cu) surfaces during the electroreduction of carbon dioxide (CO₂) to ethylene (C₂H₄). Through a combination of experimental and computational methods, the researchers found that C—C bond formation is the RDS on Cu(100), while protonation of *CO with adsorbed water becomes the RDS on Cu(111). They synthesized oxide-derived Cu(100)-dominant Cu catalysts using plasma-irradiated CuO nanosheets, achieving a high C₂H₄ Faradaic efficiency of 72%, partial current density of 359 mA cm⁻², and long-term stability exceeding 100 hours at 500 mA cm⁻². The results provide insights into the design of Cu-based catalysts for more selective C₂H₄ production via CO₂ electroreduction driven by renewable energy.The study investigates the rate-determining steps (RDS) on copper (Cu) surfaces during the electroreduction of carbon dioxide (CO₂) to ethylene (C₂H₄). Through a combination of experimental and computational methods, the researchers found that C—C bond formation is the RDS on Cu(100), while protonation of *CO with adsorbed water becomes the RDS on Cu(111). They synthesized oxide-derived Cu(100)-dominant Cu catalysts using plasma-irradiated CuO nanosheets, achieving a high C₂H₄ Faradaic efficiency of 72%, partial current density of 359 mA cm⁻², and long-term stability exceeding 100 hours at 500 mA cm⁻². The results provide insights into the design of Cu-based catalysts for more selective C₂H₄ production via CO₂ electroreduction driven by renewable energy.