Selectively intraparticle oxygen dissociation and metalloid mineralization for long-term groundwater remediation

In-situ intraparticle mineralization of widespread metalloids in groundwater is challenging but critical for global freshwater security. However, electronic and steric hindrances of complex oxygen-containing configurations prevent efficient oxygen dissociation and mineralization. Here, arsenic oxyanions are selectively and stably mineralized within d-orbital-modulated nanoscale Fe⁰ particles following enhanced d-p orbital-coupled oxygen dissociation, yielding ~100% removal efficiency, ~100% electron utilization, and ~94% metalloid intraparticle mineralization as resolved from thousands of single nanoparticles. Universal As, Sb, and Se intraparticle mineralization demonstrate excellent long-term stability (up to 98-fold of conventional nanoscale Fe⁰) in various groundwater matrices, where σ-bonded species show preferential intraparticle mineralization over π-bonded configurations. Field deployment is verified through macroscale material synthesis, minimal leaching of Fe and S in permeable reactive barriers, and economic advantages. This work establishes targeted d-p orbital-coupled bond dissociation as a transformative paradigm for metalloid-contaminated groundwater remediation and proposes a scalable in-situ remediation strategy that bridges atomic-level precision with field-ready practicality.