Balancing Dimerization and Hydrogenation Kinetics by Stabilizing Cu ⁺ and Tightening H‐Bond Network for Electrocatalytic Acetylene Hydrodimerization

Abstract

ABSTRACT The electrocatalytic hydrodimerization of acetylene (EHDA) offers a promising alternative to energy‐intensive naphtha steam cracking for producing 1,3‐butadiene but faces a formidable challenge due to kinetic imbalance between C–C coupling and hydrogenation. Herein, we balance the dimerization and hydrogenation kinetics of EHDA by stabilizing Cu + and tightening the hydrogen‐bond network over citrate anion grafted Cu 2 O catalysts (E‐CA/Cu 2 O). The X‐ray absorption fine structure, Cu LMM Auger spectrum, and theoretical simulations corroborate citrate anion modification induces electron transfer from Cu 2 O to citrate ions. This stabilizes the active Cu + sites under electrochemical reduction conditions and further lowers the C‐C coupling barrier of *C 2 H 2 and *C 2 H 3 to *C 4 H 5 . The in situ attenuated total reflection surface‐enhanced infrared spectroscopy confirms that the citrate anion also reconstructs the hydrogen‐bonding network and reduces the content of isolated water at the electrode‐electrolyte interface. The appropriate supply of active *H species effectively promotes the hydrogenation of *C 4 H 5 to form 1,3‐butadiene rather than competitive acetylene semihydrogenation. As a result, E‐CA/Cu 2 O catalyst achieves a Faradaic efficiency of 88.0% and a 1,3‐butadiene partial current density of 55 mA cm −2 , which is about 3‐fold higher than E‐Cu 2 O. This work will guide the rational design of high‐performance catalysts for regulating the kinetics of electrocatalytic acetylene hydrodimerization.