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 (CH) 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 at -1.5 V vs. RHE, greatly outperforming their counterparts with {111} surfaces exposed. Further comparisons of HO splitting and CH hydrogenation reveal that the activation of CH is a crucial factor in promoting the kinetics of ethylene electrosynthesis. Additionally, experimental and theoretical mechanistic characterizations demonstrate that stronger CH adsorption over the {100} surface strengthens the π conjugation of CH, leading to the delocalization of π electrons to promote the activation of CH for enhanced hydrogenation kinetics.