Concave surface-enriched reactant and enhanced mass transfer for electrocatalytic ethylene production from low-concentrated acetylene

Abstract Electrocatalytic semihydrogenation of acetylene (C₂H₂) provides a facile and petroleum-independent strategy for ethylene (C₂H₄) production. However, the reliance on the preseparation and concentration of raw coal-derived C₂H₂ hinders its economic potential. Here, density functional theory calculations demonstrate that a concave surface is beneficial for enriching C₂H₂ and optimizing its mass transfer kinetics, thus leading to a high partial pressure of C₂H₂ around active sites, which is suitable for the direct conversion of raw coal-derived C₂H₂. Then, a porous concave carbon-supported Cu nanoparticle (Cu-PCC) electrode was designed to enrich the C₂H₂ gas around the Cu sites. As a result, the as-prepared electrode enables a 91.7% C₂H₄ Faradaic efficiency and a 56.31% C₂H₂ single-pass conversion under a simulated raw coal-derived C₂H₂ 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 C₂H₂ coverage is revealed to result in the delocalization of π electrons in C₂H₂, consequently promoting C₂H₂ activation, suppressing HER competition, and enhancing C₂H₄ selectivity.