Ionic Liquid‐Induced Product Switching in CO₂ Electroreduction on Copper Reaction Interface

Abstract The electrochemical reduction of CO₂ (CO₂RR) mainly occurs at the three‐phase interface, and the properties of an interface can directly affect the CO₂RR pathway. Cu‐based materials can produce considerable amounts of alcohols and hydrocarbons, but it is hard to precisely regulate the reaction interface and obtain specific target products. Herein, the properties of the Cu surface through a facile strategy of ionic liquid modification are successfully adjusted. According to theoretical calculations and in situ Raman and FTIR spectra characterizations, it is revealed that the introduction of ionic liquids (e.g., [Bmim][PF₆]) can control the energy barriers and distribution density of key intermediates on Cu interface, thus totally change the reaction pathway of CO₂ electroreduction. Consequently, the dominant products from the Cu catalyst will be dramatically switched between C₂H₄ with a 71.1% Faraday efficiency (FE) and CH₄ with a 67.2% FE. It is rarely seen in previous reports that the CO₂RR products can be fundamentally changed through simple interface modifications. This work offers a straightforward approach to tune the interfacial properties and understand the mechanisms in various electrocatalytic reactions.