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

Electrocatalytic semihydrogenation of acetylene (C 2 H 2 ) provides a facile and petroleum-independent strategy for ethylene (C 2 H 4 ) production. However, the reliance on the preseparation and concentration of raw coal-derived C 2 H 2 hinders its economic potential. Here, a concave surface is predicted to be beneficial for enriching C 2 H 2 and optimizing its mass transfer kinetics, thus leading to a high partial pressure of C 2 H 2 around active sites for the direct conversion of raw coal-derived C 2 H 2 . Then, a porous concave carbon-supported Cu nanoparticle (Cu-PCC) electrode is designed to enrich the C 2 H 2 gas around the Cu sites. As a result, the as-prepared electrode enables a 91.7% C 2 H 4 Faradaic efficiency and a 56.31% C 2 H 2 single-pass conversion under a simulated raw coal-derived C 2 H 2 atmosphere (~15%) at a partial current density of 0.42 A cm -2 , greatly outperforming its counterpart without concave surface supports. The strengthened intermolecular π conjugation caused by the increased C 2 H 2 coverage is revealed to result in the delocalization of π electrons in C 2 H 2 , consequently promoting C 2 H 2 activation, suppressing hydrogen evolution competition and enhancing C 2 H 4 selectivity.