Direct Cl─Cl Coupling Over Atomically Dispersed Ir₂ Pairs for Efficient Chlorine Electrosynthesis

Chlorine evolution reaction underpins the chlor-alkali industry, yet its conventional dimensionally stable anodes (DSAs) suffer from low noble-metal utilization and limited intrinsic activity. Here, we report a molecularly precise strategy to construct atomically dispersed iridium diatomic (Ir₂) pairs anchored on MnO₂ nanorods (i.e., Ir₂─MnO₂), representing a well-defined dual-atom catalyst (DAC) for efficient chlorine electrosynthesis. Spherical aberration-corrected microscopy and x-ray absorption spectroscopy (XAS) validate the diatomic features of Ir₂ pairs with an interatomic distance of 3.16 Å. The Ir₂─MnO₂ electrocatalyst exhibits competitive CER performance, delivering an overpotential of 36.9 mV at 10 mA cm^-2 and a low Tafel slope of 34.6 mV dec^-1 in NaCl electrolyte. Kinetic analysis, operando Raman spectroscopy, and theoretical calculations collectively reveal that adjacent Ir-Ir dual-atoms synergistically stabilize two *Cl intermediates, enabling a thermodynamically favored direct *Cl─*Cl coupling mechanism. Notably, Ir₂─MnO₂ maintains satisfactory selectivity and durability over 500 h at large current densities in natural seawater electrolysis. This work breaks the technical challenges of atomic-scale dispersion and diatomic pairing of DACs, establishing diatomic site engineering as a powerful paradigm for efficient chlorine electrosynthesis.