Electrosynthesis of 1,3-butadiene from dilute acetylene over coordination-modulated dicopper molecular catalysts

Electrosynthesis of 1,3-butadiene from acetylene offers a promising alternative to energy-intensive industrial processes. Nonetheless, achieving selective hydrodimerization of acetylene remains challenging due to competing side reactions, particularly for dilute coal-derived acetylene. Herein, we synthesize a series of dicopper paddlewheel Cu₂(LCOO)₄ (L = tert-butyl, isopropyl, ethyl, and methyl), featuring bidentate bridging carboxylate ligands with specific Cu···Cu distances for electrocatalytic hydrodimerization of acetylene to 1,3-butadiene. Through catalyst benchmarking, in situ spectroscopy and computational analysis, we reveal that sequential modulation of carboxylate ligands (methyl → ethyl → isopropyl → tert-butyl) progressively enriches electron density at dicopper sites while strengthening structural robustness across the Cu₂(LCOO)₄ series. The optimized Cu₂(tert-butylCOO)₄ exhibits favorable reaction energetics for acetylene dimerization and subsequent hydrogenation, achieving 91% Faradaic efficiency with a 1,3-butadiene formation rate of 0.93 mmol h⁻¹ cm⁻² in a flow cell. For simulated production of 1,3-butadiene from coal-derived acetylene (15%) in a membrane electrode assembly system, this catalyst demonstrates 83% Faradaic efficiency at −300 mA. This work highlights an effective coordination modulation strategy for producing 1,3-butadiene via dicopper molecular catalysts.