Electrocatalytic Acetylene Semihydrogenation: Catalyst Design, Microenvironment Regulation, and Reactor Engineering

Electrocatalytic acetylene semihydrogenation (EAH), which uses water as the proton source under ambient conditions, offers an environmentally sustainable and energy-efficient alternative to conventional thermocatalytic acetylene hydrogenation for purification and synthesis of ethylene (C₂H₄). Recent advances in Cu-based catalysts and interfacial engineering in three-phase reactors have enabled EAH to achieve high Faradaic efficiencies (FE > 90%), ampere-level partial current densities, and stable polymer-grade ethylene output. This review comprehensively addresses the three pillars: (i) catalyst design for regulating acetylene/ethylene adsorption energetics and suppressing competing reactions; (ii) microenvironment regulation, including interfacial water, local electric fields, and mass transport; and (iii) the influence of reactor engineering on performance. Eventually, we provide an outlook on the current challenges and future research directions for advancing the EAH toward industrial implementation.