Surface Coordination-Promoted Electrosynthesis of 1,4-Butanediol from Ethylene and Water via 2-Bromoethanol

1,4-Butanediol (1,4-BDO) is an important chemical with growing interest due to its use in biodegradable polymers. Its conventional synthesis by the Reppe process involves the condensation of acetylene and formaldehyde, followed by hydrogenation, demanding multiple steps and stringent safety/environmental regulation. In this work, we demonstrated the electrosynthesis of 1,4-BDO from ethylene and water by coupling the reductive coupling of 2-bromoethanol (2-Br-EtOH) with the Br^- redox. The homocoupling of 2-Br-EtOH into 1,4-BDO was the limiting reaction. By a data-mining-assisted approach, we identified N-based ligands with an -NH₂ group and appropriate Fukui functions as promoters for 1,4-BDO formation on Cu electrodes. The optimal 2-aminoimidazole ligand could generate 55.1% yield and 61.4% selectivity of 1,4-BDO from 2-Br-EtOH, by facilitating surface Cu⁺ formation for homocoupling, suppressing adsorbed hydrogen formation for hydrogenation, and retarding electron injection to create a local pH gradient toward the non-Faradaic production of ethylene oxide. By integrating the anode with hydrophobic carbon for Br^- oxidation and its sequential reaction with gaseous ethylene into 2-Br-EtOH, we demonstrated the 1,4-BDO electrosynthesis under internal 2-Br-EtOH and Br^- cycling, with ethanol as the only side product. This work extends the industrial synthetic strategy toward 1,4-BDO to a safe and green electrocatalytic route using low-cost ethylene and water as raw materials.