Orbital Coupling-Engineered Coordination-Unsaturated CuAg Nanochains Drives Spontaneous Electrocatalytic Acetylene Semihydrogenation and Zn-C₂H₂ Batteries

Electrocatalytic semihydrogenation of acetylene (C₂H₂) offers a mild and sustainable pathway for ethylene production, yet it faces critical challenges including competitive C─C coupling for 1,3-butadiene due to insufficient proton supply and hydrogen evolution under high current densities. To address these limitations, we design a coordination-unsaturated CuAg bimetallic catalyst with cross-linked nanochains (Cu_0.5Ag CNCs), which synergistically regulates proton dynamics, maintaining high activity from 0.1 to 0.6 A cm⁻² and achieving an ethylene Faradaic efficiency of 95.1% at 0.5 A cm⁻². Mechanistic studies reveal that the introduction of Cu makes the d-band center in Cu_0.5Ag CNCs upshift toward the Fermi level, strengthening orbital coupling with C₂H₂ and creating a high *H demand surface. In situ spectroscopic and density functional theory analyses demonstrate that coordination-unsaturated Cu-Ag interfacial sites promote spontaneous C₂H₂ hydrogenation, especially bypassing formation barriers of *C₂H₂ and *C₂H₃. This thermodynamic superiority originates from sufficient proton supply and exothermic *H consumption for C₂H₂ hydrogenation. Furthermore, the catalyst enables a Zn-C₂H₂ battery with a power density of 2.12 mW cm⁻², showcasing dual functionality in electrosynthesis and energy storage. Our work establishes a paradigm for coordination unsaturated bimetallic catalyst design through orbital coupling engineering, providing atomic-level insights into proton-mediated reaction control for sustainable chemical manufacturing.