Boosting intermediate activation via enhanced proton supply at Cu-Bi heterometallic interfaces for high-efficient electrocatalytic acetylene semihydrogenation

Electrocatalytic semihydrogenation of acetylene to ethylene (ESAE) provides a sustainable approach to remove acetylene impurity from crude ethylene under ambient conditions. However, the key challenge lies in the difficulty of effectively controlling the intermediates states due to competitive hydrogen evolution reaction (HER), which hinders the achievement of a breakthrough in selectivity of ethylene. Herein, we present a Cu-Bi bimetallic composite catalyst (CuBiO_x), which obtains high selectivity towards ethylene production with a Faradaic efficiency (FE) of 96.8 % at a partial current density of 232 mA cm⁻². Notably, even in crude ethylene streams, it achieves an acetylene conversion rate of 99.8 %, underscoring the practical application potential in ethylene purification. Mechanistic studies combining in-situ electrochemical measurements and density functional theory (DFT) reveal that Bi incorporation enhances water dissociation kinetics and generates abundant active protons, thereby promoting the formation of key *C₂H₃ intermediate. Concurrently, the Cu-Bi heterometallic interface with the adsorption of active protons reduces the energy barrier for the conversion of *C₂H₂ to *C₂H₃, while suppressing H₂ evolution and C–C coupling. This work showcases the design and application of heterometallic composite catalysts in broader electro catalytic hydrogenation processes, indicating their transformative potential in various industrial and research contexts.