Hybrid Active Sites in Coordination Polymers Enable Ampere-Level Acetylene Semihydrogenation in Membrane Electrode Assembly Systems

Electrocatalytic acetylene semihydrogenation in membrane electrode assembly systems promises a sustainable pathway for ethylene production, yet faces challenges in catalyst performance and durability. Herein, we developed a Cu coordination polymer with hybrid sites that synergistically integrate open Cu sites and N-heterocyclic carbenes. These hybrid sites bestow the coordination polymer with acetylene gasophilicity, hydrophobicity toward water, and readily accessible active Cu sites, which energetically facilitate acetylene absorption and vinyl intermediate formation, thereby enabling efficient ethylene production at ampere-level current densities. In a membrane electrode assembly electrolyzer with pure acetylene, this polymeric catalyst achieved high ethylene Faradaic efficiency of 93.1% at −0.5 A cm⁻² and 83.3% at −1.0 A cm⁻², with stable operation for 100 h at −0.5 A cm⁻². Notably, even with a 15% coal-derived acetylene at a flow rate of 60 standard cubic centimeters per minute, this catalyst system demonstrated 64.4% ethylene energy efficiency and durable performance over 200 h at −0.5 A. This work advances the design of highly stable and active polymeric catalysts for electrocatalytic acetylene semihydrogenation.