Fluorine-regulated Cu catalyst boosts electrochemical reduction of CO2 towards ethylene production

•Fluorine modified Cu2O catalyst was obtained by thermal decomposition of CuOHF.•The surface fluorine species stabilize Cu+ and enable C2 products in CO2RR.•A Faradaic efficiency of 40.6 % to ethylene remains stable over 13 h.•Theoretical calculation indicates suppression of water dissociation by fluorine species.•Fluorine promotes hydrogenation of CO to CHO and CHOCHO coupling to ethylene. Electrochemical reduction of carbon dioxide (CO2RR) into value-added multi-carbon (C2) products utilizing renewable energy is a promising way to reduce carbon emission and achieve carbon neutrality. However, rational design of catalysts towards high C2 products selectivity remains a formidable task. Herein, fluorine modified copper catalyst was synthesised by thermal anneal in the presence of ammonium fluoride and sequential annealing in argon atmosphere. The charge distribution and coordination environment on copper surface were adjusted by doped fluorine atoms, which enables the formation of key intermediates and their sequential evolution into ethylene. The catalyst achieves a remarkable Faradaic efficiency (FE) of 40.6 % for eCO2RR to ethylene and remains stable over 13 h. Density functional theory calculations indicates that the excellent CO2RR performance can be attributed to the suppressed hydrogen evolution on fluorine-doped copper catalyst. Our work brings a potential modification strategy of Cu-based catalyst for electrolytic CO2-to-C2 pathway.