Preserving Hydrated Protons Among Electrolyte–Electrode Interface for Accelerated Electrocatalytic Acetylene Semi‐Hydrogenation

ABSTRACT Electrocatalytic acetylene (C 2 H 2 ) semi‐hydrogenation with H 2 O as a hydrogen source has been regarded as a competitive approach to produce ethylene (C 2 H 4 ) under mild conditions. However, the sluggish proton‐coupled electron transfer at the triple phase interface, hindered by water dissociation and proton transfer, restricted further applications. Here, we demonstrated that the high curvature carbon nano onion coverage can significantly regulate the reaction micro‐environment at the triple phase interface and promote the C 2 H 2 semi‐hydrogenation. The electrostatic confinement of in situ generated H 3 O + can be preserved during the electrocatalytic process at the as‐prepared gas diffusion layer (GDL) supported Cu film covered by carbon nano onion electrode (CNO/Cu/GDL). The CNO/Cu/GDL electrode exhibits a C 2 H 2 to C 2 H 4 Faradaic efficiency (FE) of 97% with an ideal stability, significantly higher than that of the graphene‐covered electrode. In situ Raman spectroscopy, combining theoretical simulation, indicates that the high curvature carbon nano onion helps to preserve the H 3 O + species and promote the semi‐hydrogen with the enriched hydrated protons. This study offers a feasible strategy to optimize the local environment at the electrode/electrolyte interface for accelerated proton generation and intermediate transfer regarding hydrated protons.