Promoting the Kinetics of Ethylene Electrosynthesis via the Facet‐Dependent Activation of Acetylene over Silver Catalysts

Metallic silver (Ag) sites exhibit a robust ability to suppress undesired C-C coupling in the electrocatalytic semihydrogenation of acetylene (C₂H₂) into ethylene (ESAE), leading to satisfactory selectivity and stability. However, the relatively low reaction kinetics still hinder its practical value. Here, the facet-dependent ESAE performance is first evaluated to increase the sluggish hydrogenation kinetics and provide mechanistic insight for subsequent catalyst design. As a result, the Ag nanocubes with {100} surfaces demonstrate a partial current density of 337 mA cm^-2 at -1.5 V vs. RHE, greatly outperforming their counterparts with {111} surfaces exposed. Further comparisons of H₂O splitting and C₂H₂ hydrogenation reveal that the activation of C₂H₂ is a crucial factor in promoting the kinetics of ethylene electrosynthesis. Additionally, experimental and theoretical mechanistic characterizations demonstrate that stronger C₂H₂ adsorption over the {100} surface strengthens the π conjugation of C₂H₂, leading to the delocalization of π electrons to promote the activation of C₂H₂ for enhanced hydrogenation kinetics.