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.