Nitridated Iron-Based (Nano)Materials for Environmental Remediation: Synthesis, Characterization, and Performance.

Iron-based materials, particularly zerovalent iron (ZVI), are widely used in environmental remediation. Still, contaminant removal can be limited by surface passivation and nontarget side reactions that compromise treatment efficiency and sustainability. To address these limitations, many modifications of ZVI have been proposed, including, most recently, nitridation (i.e., incorporation of N on the surface or within the bulk of ZVI into iron lattice). This review examines methods of nitridation (including thermochemical and mechanochemical nitridation), their effects on the morphology/physicochemical properties of iron-based materials, and the performance of the resulting materials for reduction of contaminants. Nitridation leads to the formation of iron nitrides and/or Fe-N coordination structures, enhancing dechlorination performance through different mechanisms. Iron nitrides improve electron transfer efficiency, suppress the hydrogen evolution reaction, and accelerate reductive dechlorination of a broad range of contaminants. In contrast, Fe-N coordination structures facilitate proton transfer, leading to improved dechlorination, but with different kinetic characteristics. Additionally, nitridation extends the reactive lifespan of ZVI by mitigating passivation, with iron nitrides offering direct corrosion resistance. This review highlights the potential of nitridated iron-based materials for efficient, selective, and durable remediation applications, and identifies areas for further research required to enable their widespread adoption in full-scale environmental restoration.