Edge Effects Boosting Acetylene Semihydrogenation Performance of NiN4-Doped Graphene Nanoribbon Electrocatalysts.

Conventional thermocatalytic acetylene hydrogenation relies on elevated-pressure environments, often resulting in excessive energy expenditures and suboptimal ethylene yields. In contrast, room-temperature electrocatalytic acetylene semihydrogenation (EASH) offers a sustainable route for ethylene purification. However, its industrial implementation is impeded by inadequate ethylene selectivity and concurrent hydrogen evolution reactions. In this study, Ni-based single-atom catalysts anchored on the armchair and zigzag edges of graphene nanoribbons were designed, and density functional theory computations demonstrate that edge effects can modulate the electrocatalytic ethylene selectivity of NiN4 single-atom catalysts. First, the calculated binding energy, cohesive energy, formation energy, and dissolution potential indicate that all NiN4-AC-edge and NiN4-ZZ-edge configurations exhibit excellent structural stability. Second, Gibbs free energy analysis of the reaction pathways demonstrates that the 1-NiN4-AC-edge and 2-NiN4-ZZ-edge catalysts can significantly promote the EASH reaction while inhibiting the hydrogen evolution side reaction. Lastly, electronic property computations indicate that the d-band center of the active Ni site, alongside the binding strength of ethylene, function as reliable descriptors to forecast EASH selectivity. The coupling effect between the Ni d-orbital and the C2H4p-orbital in the 1-NiN4-AC-edge and 2-NiN4-ZZ-edge configurations plays a crucial regulatory role during the ethylene desorption process. The results of this research offer theoretical support for the rapid development of highly efficient EASH catalysts and are expected to advance the industrialization of this technology.