Spin Coupled FeCo Dual‐Atom Sites Direct Selective Ozone Activation for Hypersaline Wastewater Purification

ABSTRACT Heterogeneous catalytic ozonation represents a powerful process for eliminating refractory organic contaminants from hypersaline wastewater, yet its application is restricted by two critical bottlenecks: inefficient ozone activation and lack of control over on‐demand reactive oxygen species generation. In this study, we unravel that spin‐coupling in a heteronuclear dual‐atom catalyst (Fe 1 Co 1 ‐NC) can address both limitations. By replacing one metal center with an electronically matched but magnetically inert element (Fe 1 Zn 1 ‐NC and Ga 1 Co 1 ‐NC), we disentangle the long‐conflated contributions of charge redistribution and spin coupling, and identify the latter as the decisive kinetic contributor. The spin‐polarized channel across Fe‐Co pairs synchronizes H 2 O activation at the Fe site with ozone decomposition at the Co site, steering the reaction along a spin‐compatible proton‐coupled electron transfer pathway that selectively generates surface‐bound hydroxyl radicals. Consequently, Fe 1 Co 1 ‐NC exhibits enhanced oxalic acid degradation in the presence of ozone, with a turnover frequency 21.5 times that of the spin‐decoupled Fe 1 Zn 1 ‐NC. Coupling the catalyst with a gas‐diffusion tri‐phase reactor further overcomes salinity‐induced ozone mass‐transfer limitations and enables robust, sustainable mineralization of real hypersaline wastewater. This work identifies inter‐site spin coupling as a kinetic descriptor for spin‐sensitive ozone activation and provides a spin‐decoupling strategy for the mechanistic design of dual‐atom catalysts.