Joule Heating Induced Reductive Iron–Magnesium Bimetallic Nanocomposite for Eminent Heavy Metal Removal

Fe0-based materials exhibit great power in removing heavy metals, but their passivation issues remain a challenge. Guided by the synergistic effects within bimetallic modifications, a novel reductive FeMg bimetallic nanocomposite (FeMg/NC) was constructed using flash Joule heating technology. The ultrafast heating and quenching process achieved a phase-fusional structure comprising Fe0 and Mg0 encapsulated in the resulting aromatic-carbon layer. Incorporation of highly reductive Mg0 into Fe0-based material led to an approximately 2–3 times enhancement in pollutant removal efficiency compared to monometallic nanocomposites. Experiments and theoretical calculations revealed that this augmented removal efficiency arose from the FeMg dual-site synergistic effect, facilitating the interaction between FeMg/NC and the targeted pollutants. That is, adsorption led to the directional inward diffusion of pollutants, and the outward release of electrons from this formed phase-fusion structure was accelerated via the electron delocalization effect. Therefore, FeMg/NC exhibited excellent removal capacities for typical heavy metals (including Cr(VI), Sb(V), Ni(II), and Cu(II)). This study demonstrates the flexibility of Joule heating technology for constructing bimetallic nanocomposite, which can effectively address heavy metal pollution and opens up endless possibilities for developing more impactful environmental remediation materials.