Selective electroreduction of acetylene to 1,3-butadiene on iodide-induced Cu^δ+–Cu⁰ sites

A crucial task towards creating a sustainable chemical industry is the electrification of chemical processes that produce value-added molecules. One such molecule is 1,3-butadiene (1,3-BD), the feedstock used for manufacturing synthetic rubber. 1,3-BD is traditionally derived, as a by-product, during the energy-intensive steam cracking of naphtha to ethylene. Here we introduce an alternative approach to selectively produce 1,3-BD from the electroreduction of acetylene (e-C₂H₂R). By using a potassium iodide electrolyte, we created Cu^δ+–Cu⁰ sites on a Cu₂O-nanocube-derived catalyst, which are efficacious for promoting e-C₂H₂R to 1,3-BD. 1,3-BD was formed with a Faradaic efficiency reaching 93% at −0.85 V versus standard hydrogen electrode (SHE) and a partial current density of −75 mA cm⁻² at −1.0 V versus SHE. Density functional theory calculations show that I⁻ preserves Cu^δ+–Cu⁰ sites, which facilitate the favourable binding of acetylene, leading to 1,3-BD formation through the coupling of *C₂H₃ moieties.