Ethylene electrosynthesis from low-concentrated acetylene via concave-surface enriched reactant and improved mass transfer.

Electrocatalytic semihydrogenation of acetylene (CH) provides a facile and petroleum-independent strategy for ethylene (CH) production. However, the reliance on the preseparation and concentration of raw coal-derived CH hinders its economic potential. Here, a concave surface is predicted to be beneficial for enriching CH and optimizing its mass transfer kinetics, thus leading to a high partial pressure of CH around active sites for the direct conversion of raw coal-derived CH. Then, a porous concave carbon-supported Cu nanoparticle (Cu-PCC) electrode is designed to enrich the CH gas around the Cu sites. As a result, the as-prepared electrode enables a 91.7% CH Faradaic efficiency and a 56.31% CH single-pass conversion under a simulated raw coal-derived CH atmosphere (~15%) at a partial current density of 0.42 A cm, greatly outperforming its counterpart without concave surface supports. The strengthened intermolecular π conjugation caused by the increased CH coverage is revealed to result in the delocalization of π electrons in CH, consequently promoting CH activation, suppressing hydrogen evolution competition and enhancing CH selectivity.