Amorphous MoO_x Interfaces Activate Pt Nanoclusters for Ultralow-Overpotential Chlorine Evolution

Direct seawater electrolysis offers a pathway to co-produce hydrogen and industrial chlorine, yet chlorine evolution at low chloride concentrations is limited by sluggish halide activation and rapid Pt dissolution under oxidative conditions. Here we show that in situ amorphization of molybdenum oxide dynamically reconstructs the metal-support electronic interface, generating Pt nanoclusters with cooperatively enhanced electronic metal-support interaction and lattice tensile strain. This electronically reconfigured interface simultaneously strengthens chloride adsorption, stabilizes Pt against chloro-complex dissolution, and promotes early formation of reactive Pt-Cl intermediates. As a result, the amorphous-interface catalyst achieves nearly 100% chlorine selectivity, an overpotential of only 65 mV at 10 mA cm^-2 in seawater, and a mass activity 26-fold higher than Pt/C. Operando Raman spectroscopy reveals pre-equilibrium halide activation preceding chlorine evolution, consistent with a Volmer-Tafel mechanism enabled by adjacent electronically coupled Pt sites. These findings establish amorphization-induced electronic interface engineering as a powerful strategy to simultaneously activate, stabilize, and synergistically accelerate electrocatalytic halogen evolution.